Hahahhh!!! I was legit gonna say “Ember Island.”
How silly do you want it to be? What I’m thinking sounds pretty heavy until you get to what you would literally be writing.
I’m imagining a group of kids in a “home,” orphans (children who are accused of being mentally unstable) who couldn’t deal with the reality of their lives and imagine (not imagine… Genuinely believe) they have elemental powers. (Think, Pan’s Labyrinth.)
They’re all held in separate wings. All the orphans can be from different places with different backgrounds and beliefs and they want to unite all the children to fight against the older kids (like Azula and Zuko) and the orderlies (Ozai) to free all the “nations” and unite the “world.”
The kids are convinced they’re using powers, and truly believe bending is real-- but the reality would look hilarious. “Bending” with no result- convinced their “powers” are obliterating the enemy (think Dinner for Schmucks). Hahahah! Please tell me you’ve seen that movie so you can share my vision!!! Everyone involved has to be convinced the bending is real. That’s the only way something that depressing could be funny.