PLEASE READ THIS BEFORE ASKING QUESTIONS IN COMMENTS:
I wrote this guide more than one year ago, when I was still playing Retribution seriously. I haven't played the game for months now, and I'm not planning to go back to it.
This means that I won't be able to answer to comments as I'd like to, and I'd rather not answer than writing something not tested/made up.
Therefore, I am sorry but I won't answer to comments anytime soon. It may still happen that I'll go back to the guide and to this game.
Thanks anyway for commenting and reading the guide.

Ah, the Shas'O Commander. My favorite hero and the only one which I've actually elited 3 times.
This big guy packs a hell of a punch and is probably the best DPS hero in the whole game, but remember that he has 0.0 (zero) melee damage, as well as armors with lower ratings than those of most of the other heroes. The upper side is the fact that each armor has jets, which allow you to jump around the map with a small expense in energy, thing that will almost always save you in a pinch.

How to use this hero? The Tau has to stay in cover until faster melee units reach him, dealing as much ranged damage as possible while the rest of the team either deals with the melee or helps with ranged damage (the Command Suit is just perfect for this). When things get hot, jump-jump-jump away to safer tides and start shooting again.

Bear in mind that you're using one of the strongest heroes in the game, which means that matches will become easier and you'll net more kills. This also means that Colosseum becomes usually quite harder because your clone is just as good. Moreover, even though this hero is actually pretty easy to start with, you'll need some time before you'll be able to kite effectively (i.e. survive longer).

At the bottom you can find the loadout I've used as well as my tactic when I did the achievement "Tau Efficiency". Good luck with that.

The guide is a work in progress, even though most of it is already where it should. It will be updated whenever I feel like it.

I'll just skip the description of the equipment, you can read it in-game. In the weapons section I put every thing that goes in weapon slots, which includes shields and the twin link. Please be aware of the fact that those below are my opinions about these weapons, so if you don't agree write it down in the comment section.

GOOD WEAPONS
Commander Issue Plasma Rifle
Starting equipment, and yet probably the best weapon available. High damage, armor piercing, high accuracy and wide range, with this weapon you'll be able to both rack up lots of kills with weaker enemies and take down heavier opponents. When twin linked, this weapon becomes even deadlier. As you'll see, I use it almost in every build. If you improve the accuracy with the appropriate accessory you will almost never miss even when moving. This weapon is also Armor Piercing, which means that it will ignore a good deal of the target's armor, thus dealing more damage even to armored enemies.
Remember that when playing Colosseum your clone will have this weapon as well (obviously) and so it will be extremely dangerous in ranged combat, with a high-damage weapon, high accuracy and huge range. Try to focus it at the beginning of the wave, better if you have a tanky melee character able to keep it occupied.

Flamer
Again starting equipment, this flamer is a bane for any kind of light infantry and a threat even for heavier foes thanks to a small armor piercing bonus. The drawbacks are an extremely small range (as expected) and little-to-no effect on the most armored enemies. Moreover, if you don't use the NWI (see later) your damage output won't be as high. Try to couple this with the AA missiles.

Burst Cannon
Unlocked at level 16. If single-wielded and without the Command Suit, this weapon isn't actually that good: low damage and no armor piercing mean that you'll be taking a long time to kill even lesser foes, let alone bigger enemies. When paired with dual-link and a Command Suit, things get much easier. You can dispatch almost any non-fearless enemy (which means, almost every one of them, with the exceptions of the Tyranid warrior brood and all the vehicles) in a matter of seconds. With the support of some other hero you'll be able to damage even tougher enemies. Just remember than in this way you'll become an extremely squishy target for almost any kind of enemy, especially without Stimulants. Couple this weapon with AA missiles if you need even more Armor damage.

BAD WEAPONS
Fusion Blaster
Unlocked at level 3. This one sucks, really. Higher damage and armor piercing power aren't a good enough trade-off for an extremely low ROF and a terrible range. Stick to the Plasma Rifle, I mean it. If you absolutely need to use this weapon, then do it in Anvil, at least here there are vehicles to shoot. Only in this case this weapon has an use, but I still rather use the Plasma Rifle and AA missiles. Terrible, terrible range. Remember also that this weapon has 75% accuracy, which means that, in average, you'll miss a shot every 3. This, coupled with the extremely low RoF makes you defenseless until you can shoot again and in constant danger from mobs of weak melee units. We're not even talking about taking down targets in cover. Like in the Commander Rifle case, by improving the accuracy this weapon will almost never miss, but its usefulness won't improve as much. If you're using this weapon, the AA missiles mean overkill. Choose the Frag missiles in this case, since you lack any kind of mean to counter light infantry.
Yet another reason for avoiding this weapon in Colosseum is the fact that a clone armed with this will probably OHK the entire party in a matter of seconds, especially when twin-linked.

Airbursting Fragmentation Projector
Unlocked at level 9. I really hate this one, but maybe it's not even that bad. It is just perfect for slow, ranged, light infantry and sucks on everything else. Even when twin-linked. The shot/projectile/bomblet/whatever is too slow to hit and if it misses, no damage dealt whatsoever. It deals close-to-zero damage to vehicles and heavily armored enemies, so don't expect to use it against anything stronger than a nob. If you actually manage to take down one. Things change if you're playing with another strong ranged character, hopefully one who can tear down armored foes. In this case, this weapons passes from BAD to MEH, if used as a support weapon and nothing else. Because of the direction of the explosion, the damage will be dealt in a small area under and beyond the explosion, which means that it will probably hit infantry moving away from you.
If you really want to use this, please pair it with AA missiles. If you use anything else, you might even survive till the next waves, but then your damage to armored enemies will be totally negligible and without a party member able to dish it out you'll be screwed (as an example, a Carnifex will regenerate health faster than your ROF, so you won't be able to take it down in any way).

SHIELDS
Shield Generator
Starting equipment. It should be used just until you unlock either the Repulser Shield or the Twin-Link. In any case, never, ever, use the ability. The shield resistance is terrible and a hit strong enough (e.g. Wraithlords, marine scouts' grenades, carnifex blades and so on) will be able to pierce through your defense, as well as completely deplete your energy pool. Which means that you can't jump away, and this makes you basically a dead Tau. Armor (+50) and HP (+25) bonus aren't bad, just don't use the ability.

Repulser Shield
Unlocked at level 7. While the armor and HP bonus are the same, the ability is way better than the Shield Generator. For 15 energy you get the Kinetic Pulse, which knocks down most infantry units (but doesn't knock down Assault Space Marines, duh) and wipes out lighter units. It can also be used when raising a point/reviving a teammate without interrupting the action. I don't really like this shield, but it's probably a matter of taste. I'd rather use energy otherwise.

Iridium Plated Shield
Unlocked at level 11. One of my personal favorites, either I use this or the Twin Link. Awesome in a defensive build, it boosts both HP and Armor, increasing the Heavy Jet damage as well, which means that with the Coolant Injectors equipped you can use the jets to stomp over infantry dealing damage and stunning them. Lovely thing, especially if camping in a gate in higher waves.
You can't pair this shield with the Agile Suit.

Networked Weapon InterfaceUnlocked by achievement "Dynamic Entry". Graints the trait "Twin Link", named countless times before. This goes in the shield section just because it's equipped instead of one. It doubles any weapon used by the commander, and each one can hit a different enemy. The downside is losing the bonus given by the shields, making you an easier target, as well as reducing the power output of the single weapons. In Anvil losing the shield becomes a problem, while in Colosseum there aren't that many enemies and this can be used without it being too much of a danger to survival. Keep in mind that by using this you almost double your firepower so if in your team there is an healer or a tank the DPS output outweighs the loss in resilience.

IMPORTANT NOTICE:
As you've probably already figured out, every Suit of the commander provides you with the Unshakable trait, making you immune to knockback. This would be pretty cool, if only it worked 100% of the times.
Unfortunately, this is not the case. It may happen (and it happens quite frequently, frankly) that when you are hit by an attack which should knock you over the trait does not kick in. This leaves you defenceless for some seconds, i.e. the same time it takes other heroes to pick themselves up after being thrown to the ground, not allowing you to either return fire or jump away.
For this reason, you should be always very careful in waves which spawn Storm Boyz, Rokkit Launcha, Catachans, the Seer Council. You should keep an eye on any kind of unit with a knockback skill, but those I've mentioned are the worst ones.
From my experience, whenever you notice that there are either Rokkit Launcha's or Storm Boyz in the map you should start jumping around the map without stopping in the same place for too long.
This is the main problem with the Tau armors and you should keep this in mind whenever you play with this hero.
This glitch could actually happen when you start jumping and you are about to be hit by something. In order to avoid this, jump even earlier or wait to be hit then engage Jets.
Thanks to ♪Zero Fata for noticing this.

XV8 ‘Light’ Crisis Battlesuit
Starting equipment. I'm pretty sure I've never equipped this even once, since even when I started a new elite level I used the Armored Suit. This suit is, in my opinion, completely useless. It makes you faster on foot, but if you're playing with the Tau commander your primary mean of transport should be your jet ability, not your basic movement. Because of this and the fact that it is one of the lightest armors you can use, you should just avoid it altogether and use the Armored Suit instead.

XV8 ‘Armored’ Crisis Battlesuit
Starting equipment. This armor will probably stay with you until you unlock the Command suit, and even beyond that level. It gives you more armor than any other suit, as well as the trait "Heavy Jets". The trait lowers the range of the jets, which indeed is an issue when you are kiting, but increases your weight as well. This means that when you jump in the middle of a group of infantry you'll send them flying, stunning in a small radius around your landing point as well.
Try to use the stun as much as you can, and remember that it works on clones as well.

XV8 ‘Agile’ Crisis Battlesuit
Unlocks at level 13.
Low armor rating, but still awesome if you want to spend more time flying than on the ground. The "Superior Stabilizers" trait increases the range to an almost map-wide level, reducing the cost of "Jets" as well (which become actually free if you use Coolants, and you should). The main problem with this suit is the fact that the armor rating is quite low and so you are more squishy than when you use the Armored suit. Way better than the Light Armor, still not good enough to be used consistently. Quite fun to mess with, though.
You can't pair this suit with the "Iridium Plated Shield".

XV8 ‘Command’ Crisis Battlesuit
Unlocks at level 17.
One of the last unlocks as well as one of the best ones overall. This Suit doesn't grant you an hp bonus like the other 3 did, but it gives you and any ally within a pretty good range a 15% bonus to ranged damage, and that's a lot. It makes you and the allies in range immune to suppression as well, but since suppression can be broken by jumping, this is not vital for you, it may be so for a hero without a movement ability. You can check whether your allies are affected by the buff by looking at their hero, if there is a light blue circle below them then they are within range.
No Heavy Jets trait means that you cannot stun enemies, but at the same time that you can jump further than before.
This, together with the Armored suit, is my favourite choice when using the Tau. If I want to go full DPS, this is my first choice. You'll notice that by using this all your weapons will become even deadlier, and the Burst Cannon in particular will start dealing the damage you would expect from it.

Photon Grenades
Starting Equipment. I don't really like them, it's true that you can confuse enemies but that goes for the clones in Colosseum as well, which can stun you as much as you can stun them. The energy cost is quite high (25) so I usually replace them as soon as I can.

Snare Mines
Starting Equipment. I started using them for a while with the Coolants but I left them because of a bug which sticks the commander where he is for a while, with him not moving, shooting or using abilities. That's pretty dangerous and it happens when you issue a command too soon after using the ability.
Besides this, they're not that bad in a low level loadout since they can keep fast units at bay until you jump away, and even in Anvil it can basically block an entire wave in its tracks. Nonetheless, the danger of being stuck when you can't escape is too big for me to suggest this accessory if you can choose something else over this.

Stimulant Injector
Unlocks at level 4. Probably the signature wargear of the Tau Commander, since even when you're playing a different hero you'll hear something along the lines "Stimulants Injected" to warn you that he's in a pretty bad situation. The effect of the stimulants is healing 100 hp of the commander when he slips under 20 hp, with a cooldown of 30 seconds (not shown anywhere).
Well, I don't really like stimulants. When I'm using them, if I really need to use them I think that I'm doing it wrong. Which means, I've been taking too much damage and so I must change my strategy. In these situations I literally start counting 30 seconds while I jump around the map before doing anything else. The best scenario would be clearing the map without even having to use them.
Remember also that if a hit is powerful enough you'll die without the stims even kicking in, with enemies like Wraithlords and Carnifexes in Colosseum (as well as every high power ability of the clones, but that's way harder to do) and Predators, Land Raider, Avatar, Great Unclean One in Anvil. Beating the clone wave with stimulants is even harder as well.
All of this being said, the stimulants are still one of the accessories of choice for a tanky character and for other builds. I still don't like them anyway, and I've managed to complete both maps without using them.

Ion Battery
Unlocks at level 6. Extremely useful accessory, for 10 energy (5 with coolants) a small battery is thrown on the ground, regenerating energy for any ally within range. The total recovered energy is around 30, so it's not a complete refill. Still, this should be enough to use low energy abilities such as movement abilities, which may save your life when kiting for survival. I usually use it with builds which don't need stimulants.
Remember that by bringing these to the field the other heroes will be expecting you to give them energy, so don't forget about that.

Fragmentation Missile Pod
Unlocks at level 8. I don't like this pod, it costs way too much (30 energy) for what it's worth. The missiles have travel time as well, so try to use them on static enemies. The damage done on armored targets and vehicles isn't negligible, but I wouldn't suggest using it in anti armor role. You can wipe out blobs of infantry in one hit, but as soon as vehicles and heavier enemies start spawing the effectiveness will decrease a lot.
I'd always choose the AA missile pod over this.

Coolant Injectors
Unlocks at level 10. By far, my favorite accessory in Last Stand. The 5 seconds decrease in cooldown means that every kind of jet will cool down even before the landing, while 5 energy less for each jump allows you to jump around the map without running out of energy too soon. A must have, and you'll see later that I always use it in any loadout. When coupled with a heavy jet (Armored Suit or Iridium Plated Shield needed) you'll be able to take down light melee units just by jumping on them. Improved Jets become free as well.

Anti-Armor Missile Pod
Unlocks at level 12. Probably the second most-overused accessory, the AA missiles deal an extremely high damage to a single target and has a very small AoE. This means that you can use it on clustered enemies, and with some luck you'll be able to take them down with only one hit (this applies especially to raveners, nobs, wraithguards). A good hit is able to OHK a nob and a Leman Russ if you hit it on the sides or on the rear, while 2 hits are needed to take down Deff Dreads and Wraithlords. Be VERY careful when aiming raveners, if they Burrow and hit you the missiles WILL follow them to you, usually OHK you. It really happens.
Keep in mind that by using this accessory in Colosseum your clone will become extremely dangerous, with an ability which can OHK most heroes from halfway across the map: the wave will become harder but still doable, as long as you focus the commander as much as possibile.
This accessory is also your best bet when attempting Tau Efficiency.

Target Cluster
Unlocks at level 14. Generally underestimated, this accessory becomes extremely useful when used together with twin-linked Plasma Rifles (in the loadout section I've written a set which uses this).
Please note that the +25% accuracy isn't actually the starting accuracy + 25%, but rather standard accuracy + 25% of the standard accuracy, e.g. the Plasma Rifle has 75% standard accuracy, with Target Cluster has 93% accuracy so (75 + 75/4 = 93). This means that the flamer and the Airbust Projector won't benefit from this since they already have 100% accuracy, and the Burst Cannon won't get enough of a bonus to justify the loss of an accessory slot.

Markerlight
Unlocks at level 18. This accessory is extremely fun to use and quite good against infantry, while it's not really that good vs. vehicles. The energy cost is quite high (40 energy), but if you manage to mark enough targets you can basically nuke the entire map. And that's lovely.
The Mark Target ability when used with Coolants is free and has no cooldown, so you can jump around the map marking everything just to bring the rain upon the enemy. Marked targets receive more ranged damage so it's a win-win.
The problem with this is that a barrage hits EVERYTHING with a marker, which includes you and the other allies if they've been marked by clones in wave 16/20.
In the loadout section I've put a set which I've used and that was a lot of fun to play with.

Nano Technology
Unlocks at level 19. I used to avoid this accessory, but after playing with it a while I found out that it is a good choice if you can't expect all that support from your teammates. Moreover, the fact that you can heal them can help in a pinch, and since the effect is always active it can be better in some cases than stims are, since there is no cooldown. In a tanky build, though, stimulants would probably be a better choice.

The drones,Tau's little pets, can be powerful as a ravener as well as a complete waste of energy if misused. They also need more baby-sitting since they tend to lure the attention of any enemy in sight, shattering like glass in almost any situation, whereas other minions tend to survive a little longer. So, let's learn how to use them!

Shield Drone. Unlocks at level 5
High energy cost (35 energy is quite a lot), for a 50% ranged reduction inside the range of the shield. Good choice if you expect to camp in a corner, not that good if you kite consistently around the map, since the drone will follow you potentially breaking up cover and drawing fire from basically any melee enemy in the map. The high cost prevents a repeated use, so try to keep it safe and don't waste energy if the situation looks like it will blow up too soon. Rather, use it when you really need cover.
This drone works extremely well if you want to exploit the bug in Colosseum (see later).

Heavy Gun Drone. Unlocks at level 15
The summon cost is a bit lower (25 energy), but it is less effective as well. Sure, it will bring down weak infantry like a charm, but it's next to useless against more armored threats and has again the same problem of gathering attention from the whole wave. It should be chosen if you really want to go all out DPS and your teammates can help you protecting the drone. If you want more sustainability you should choose the shield drone instead.

Marker Drone. Unlocks at level 20
The summon cost is the lowest out of the 3, with only 15 energy (10 with coolants) required when using the ability. This drone can be destroyed by literally anything, and won't either kill or protect you from hits. The only thing it does is marking random enemies on the map, which is quite useful if you're using the Skyray Barrage, way less useful if you're not using it. But really, why should you use the marker drone without barrage, if you haven't unlocked the advanced drone controller?

Advanced Drone Controller. Unlocks by completing the assignment "Tau efficiency"
The advanced drone controller adds an additional ability to the commander depending on the drone he has equipped:
* EMP Field (Shield Drone) — EMP field locks down all shield drones and anything under their radii. Anything locked down in this way cannot attack, move, take damage, or use abilities.
* Overdrive (Heavy Gun Drone) — Overdrive temporarily increases the damage and reduces the cooldown of guns drones to zero.
* Self Destruct (Marker Drone) — Forces all marker drones to self destruct causing a powerful explosion.
This one is an accessory, but I decided to put it together with the drones since it probably belongs more here. Probably the hardest achievement out of all the LS ones, it is also one of the best pieces you can unlock by completing objectives (I'd say on par with the Lightning Claws of the Captain and with the Behemoth Claw of the nid, and of course the Twin Link described above) if you know how it should be used.
Keep in mind that the ability which will be activated will depend only on the drone equipped by your Commander, and it won't affect different drones (e.g. you have the Shield drone, another Tau uses the Marker drone, only yours will be affected).
If you're equipping the Shield drone, by using the EMP you can lock most of a wave and obtain some breathing time, though the fact that the enemies don't take damage can be an issue.
If you use the Gun drone, the damage output increases a lot: consider using this (as long as you have the accessory) if you're playing with another Tau commander who can use the gun drone since both drones will receive the buff and the damage dealt will become substantial.
The two solutions above can be chosen, but usually people with this accessory (me included) use it with the Marker drone. Why? Because it becomes one of the strongest explosives in the whole game, being able to obliterate any kind of infantry except the extremely heavy ones, as well as dealing a massive amount of damage to vehicles as well. Enemies not directly caught by the blast can be thrown halfway across the map and you can easily wipe out the clones in wave 16 Colosseum by blowing up your drone together with your clone's one. Keep in mind that it deals a lot of friendly fire as well, so try to avoid using it close to your teammates if you don't want to wipe out one of them. You can also suicide if you stand too close to it, so be careful also with that.
For a more precise description of the tactics you should use with the above configuration check the loadout section.

Additional remarks regarding the Marker Drone/ADC combo:
- The explosion damage is usually enough to incapacitate or deal A LOT of damage to any hero in the game, so pay attention to your teammates and tell them to stay clear of the explosion before the start of the game, or at least before blowing them across the map.
- Right after starting the self-destruction of the drone you are extremely susceptible to stuns/hits/melee which may prevent you from jumping. If you can't jump, you're probably dead. If you're quick enough, though, the stun from the Heavy Jets should be stil active for you to jump away.
- Hero deaths caused by the drone aren't registered by the game. Really.
- If there are other Tau in the party who are equipping the Marker drone, then don't use the ADC. You'll blow drones and owners together with yours.

How about that spot in colosseum?
Near the building in the bottom of the map you can deploy a drone between the rocks and the cliff by clicking with the cursor just below the rocks. By doing this, some of the rubble will blow up and a green cover spot will appear. You can place the drone there and it will be protected from melee units. A Shield drone will be able to resist for a very long time thanks to the ranged bonus, while the gun drone is usually too squishy to survive focused fire. The marker drone just doesn't belong there. Using that spot may be considered cheap, but keep in mind that it can act as an extremely effective decoy if the situation gets hairy: just jump in range, drop the drone and run away. Most of the enemies will focus the drone forgetting about you, leaving a little bit of freedom which can be used for reviving fallen teammates.

After talking about wargear, it's time to put everything together and go winning some matches. I'll put some of my favorite loadouts, along with some tactic to use them with success. I'll also write whether I've been able to win a game with that particular set. As you'll notice, in every loadout I'm using Coolant Injectors, and I like considering them vital for any loadout, be it DPS or tanky. I mean, 5 seconds less for every ability? That means jumping everywhere without worrying about cooldown! It's just as cool as it sounds.

The Survivalist
Let's start with the one I'm using right now. It's (almost) all about survival, which means that you won't be able to dish out as much damage as a Tau possibily can. This works in Anvil and probably won't work in Colosseum because the clone would be probably too fat to handle.

-Commander Issue Plasma Rifle
-Iridium Plated Shield

-Armored Crisis Suit

-Ion Battery
-AA Missiles
-Coolant Injectors

-Shield Drone

Tactics:
The Shield and the Armored suit boost your HP to the maximum possible for the Tau, and give you an armor value which is pretty high even for heavier characters (e.g. Tank Captain, Tank Tyrant). The Heavy trait means that you can dispatch and stun a lot of light infantry just by jumping onto them, and this helps racking up kills with squishy enemies. The shield drone should be used especially in the case of a team which can camp in a corner without being overwelmed, otherwise use a Gun drone and let it follow you around the map. The battery is useful when kiting, just jump in a spawn point, use the battery and recover energy for the AA missiles. Use these ones on any kind of heavy unit and then jump away from the fray. This kit is probably better for a support player trying to survive heavier waves by stunning and fleeing, while your team deals the real damage.
In short, hit with the AA missiles, jump, recover energy and keep doing so until the wave ends.

Complete at level 11

Works in Anvil? VERY well
Works in Colosseum? Didn't try yet, probably not.

The Sniper
I'm having so much fun with this one, a bit ligher than the one before but able to rack up 150+ kills more than the loadout above in every match without problems. Remember though that in higher waves you'll have to rely on your friends a lot more, since you lack the AA damage given by the missiles and the Armor given by your shield. If you really want to go all-out DPS, use the Commander suit instead of the Armored one: you'll become something like a walking death machine made of glass, so behave accordingly, and forget to use it in Anvil, unless you're playing with a nurse/tank who can really soak up damage for you.

-Commander Issue Plasma Rifle
-Networked Weapon Interface (NWI)

-Armored Suit/Commander Suit

-Coolant Injectors
-Target Cluster
-Stimulants / Ion Battery

-Shield Drone

Tactics:
The Target Cluster raises the Plasma Rifle accuracy to 93%, which means that you'll almost never miss a target out of cover or in yellow cover. This, together with the fact you're using the NWI allows you to mow down light infantry and heavily damage heavy units. Since you can't resist as much damage you'll have to jump a lot more, avoiding heavier units. The Stimulants can be opted out if you have a healing party, otherwise they're strongly advised.

Works in Anvil? Yes
Works in Colosseum? Instead of Stimulants use the AA Missile and it could work.

NUKE THEM
This is more for fun that anything, but with a good team I managed to beat both maps using this loadout.

-Commander Issue Plasma Rifle
-Networked Weapon Interface (NWI) / Iridium Plated Shield

-Armored Suit

-Coolant Injectors
-Markerlight
-Ion Battery

-Marker Drone

Tactics:
Jump around, mark as much as you can, jump around, mark even more, rain death, drop a battery, recover energy, repeat. For even more jumpy fun, switch the Armored Suit with the Agile Suit. Not that serious, but if your team can handle itself, you can rack up tons of kills and be a general annoyance to both friend or foe. Probably one of the loadouts with which I've had more fun playing.

Works in Anvil? Maybe.
Works in Colosseum? Yes, with a good team.

The carry
Sure I have a ♥♥♥♥♥♥ taste when it comes to names, don't I?
With this you can do stuff almost impossible to most heroes, with the exception of the nid and of the eldar (provided that your team can at least kill some enemies) in some cases.
With the following loadout you can solo till the last waves in Colosseum and generally carry games on your own until you die, if your teammates can't do a thing. They'll probably die a lot, but they will also earn exp, so hey, they should be happy anyway.
Needless to say, if you actually can build this loadout this means that you have unlocked the Advanced Drone Controller, so you can probably use the Tau pretty well by now and such a guide should tell you mostly stuff already known to you.
This kind of loadout is actually a cheap way of playing, you'll probably annoy the hell out of your teammates in different ways and the drone self-destruction is definitely overpowered. This doesn't stop me from using it from time to time though :P

-Commander Issue Plasma Rifle
-Iridium Plated Shield

-Armored Suit

-Advanced Drone Controller
-Coolant Injectors
-Nano Technology

-Marker Drone

Tactics:
Jump on clusters of enemies, drop the drone, blow the drone. Repeat. Remember that the drone takes a short while to explode, so if you don't screw up the jump you'll be able to run away with no damage dealt to your hero. With this you'll be able to OHK wave 16 in Colosseum, provided you don't do any kind of error and you're quite lucky as well: jump in the middle of the clones, drop the drone, jump away, wait for the enemy commander to drop the drone and blow everything up. If you manage to do everything well you can complete the wave in a matter of seconds, if it goes wrong you'll probably die and lose the match as a result. Since the drone takes some time to explode, try to lead your enemies in order to deal the maximum damage. You should rely on the jets as well, stomping and stunning as much as you can.

Complete: lv 20, and whenever you manage to complete "Tau efficiency".

Works in Anvil? Yes
Works in Colosseum? Yes.

The carry v2.0
- Plasma rifle
- Twin linked

- Heavy armor

- Target Cluster/Stimulants
- Coolants
- ADC

- Marker drone

suggested by Zero Fata.
I guess this works even better than the one above.

The hardest achievement in Last Stand, by far. You can do this only in Bloodied Colosseum, of course, and when you play with 2 teammates lacking in armor. This means usually Farseers/IG/Sorcerers (as long as he's not using Robes of the Deathless)/Mekboys without Boss Pole.
You'll need a good degree of luck, as well as the correct loadout.

Your loadout should look a bit like this:
-Commander plasma rifle
-Twin Link

-Command Suit

-AA missiles
-Coolant Injectors
-anything besides Stimulants

-anything.

Why the loadout above? The plasma rifle will allow you to dish out damage, the command suit will help you with that and has a lower armor rating than the armored suit, as well as no hp bonus, the AA missiles will kill the clones and the coolant injectors will allow you to shoot those AA missiles faster. Using the stimulants means voiding any damage done to the Tau clone, thus making the achievement impossible.

Tactic:
This relies COMPLETELY on your knowledge of the gate where the clones will spawn. Remember that you can tell which one it is by keeping in that it is the same gate which spawned the Banshees (weak melee eldar infantry) in wave 9.
When wave 15 is about to end, jump close to the clones' gate. As soon as the wave ends, no cooldown whatsoever, the clones will spawn.
As soon as they spawn, shoot your AA missiles at them, then close in and shoot with the weapon. When the cooldown on the AA missiles ends, shoot them again.
If you're lucky, you'll be able to kill one or two of the clones with the first salvo, then with the second you should kill the last ones. If you don't manage to do that, you have probably failed.

The most important points are:
- the team must have LOW armor overall, no tanks
- avoid stimulants
- getting close to the spawn gate (gate which spawns banshees during wave 9) before the end of wave 15
- shooting AA missiles as soon as the clones appear and then as soon as the cooldown ends

Good luck, it won't be easy.