This is the list of bosses and powerups for the Boss Rush in order.
ボスラッシュで登場するボスの、登場順リスト。所持パワーアップも併記。

1. Class C Guardian
   powerups you have: nothing
   
   
2. Queen Beetle
   powerups you have: nothing
   
   
3. Scrapping Unit
   powerups you have: Jump Booster
   
   
4. Goliath Jelly
   powerups you have: Jump Booster, Hookshot
   
   
5. Serpent 5
   powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot
   
   
6. Overgrowth
   powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot
   
   
7. Class D Guadians
   powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H
   
   
8. Tomb Spider
   powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H
   
   
9. Robed Statue
   powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H
   
   
10. Station AI
    powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H
    
    
11. Plague Hive
    powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H
    
    
12. Security Overmind
    powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H, Dash Booster V, Triple Shot, Plasma Field
    
    
13. Mender Unit
    powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H, Dash Booster V, Triple Shot, Plasma Field, Supercharge Module
    
    
14. Class A Guardian
    powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H, Dash Booster V, Triple Shot, Plasma Field
    
    
15. Multicore
    powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H, Dash Booster V, Triple Shot, Plasma Field
    
    
16. Mwyah
    powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H, Dash Booster V, Triple Shot, Plasma Field, Supercharge Module, Dash Booster X
    
    
17. The Virus
    powerups you have: Jump Booster, Hookshot, Propeller Upgrade, Charge Shot, Dash Booster H, Dash Booster V, Triple Shot, Plasma Field, Supercharge Module

Cannot beat the boss rush ?
You can use the bike when you enter.
It can kill some bosses in one shot.
These bosses are Goliath Jelly, Serpent 5, Overgrowth (the 3rd form), Class D Guardians, Tomb Spider, Robed Statue (the 2nd form), Station AI, Plague Hive (the 3rd form), Class A Guardian Shell Unit 1 and Shell Unit 2.
Thus you can see it rushing you in the new game+ boss rush ending, I guess.

ボスラッシュがクリアできない？
バイクに乗ってから挑みなさい。
横から体当たりするだけで一撃で殺せるボスがたくさんいる。
具体的には、Goliath Jelly, Serpent 5, Overgrowth (第 3 形態), Class D Guardians, Tomb Spider, Robed Statue (第 2 形態), Station AI, Plague Hive (第 3 形態), Class A Guardian, Shell Unit 1 と 2。
2 周目ボスラッシュのエンディングは、恐らくこの伏線。

If you beat the boss rush in New Game +, the ending is the same as the asteroid ending except what rushes you.
Not in New Game+, you can see a special dialogue with the virus.

強くてニューゲームの場合は、Asteroid ending になる（ただし、小惑星ではなく別のものが突っ込んでくる）。
強くてニューゲームではなく 1 周目でクリアした場合、The Virus からの特別な科白が聞ける。