There are two base requirements to achieve cherry
1. You need to have beaten the game
2. You need to have 1000 stars

Once you are ready, you need to find Pongo.

Hints (You don't need to do any of the following if you want to just reach Pongo):
1. A lumarian on the lamp switch will turn off the light for a citizen
2. No one will request the light off, you need to become a citizen by gaining enlightenment
3. Gain enlightenment by going to the ceiling lamp on the left side and mini against the pole. Jump your way to the top
4. So you've become a citizen, go turn off the light and speak with the new denizens that show up. One will have something to say about Pongo
5. The Din speak very literally, "Pongo is the true power behind the throne"

So where is Pongo?
Pongo is behind King Mittens. Jump behind his throne, walk up against the wall and go mini. After that it's as simple as talking to him and going up to the clock to turn in the 1000 stars