So, here are the rules we've got so far, in loose order of importance:
No bunnying. Your actions are your own only. The only people that can control the actions of others are Trainers with NPC pokemon.However, Pokemon are encouraged to obey their trainers, and your trainer can force you to use a move once in a while as is reasonable.
No powerplaying. Don't act like this is a wifi battle; just because someone likes Delcatty a lot, does not give you the right to kick the crap out of them because you have/are Blaziken.
Legendaries may, at some point, be controllable, but are prohibited from usage by most players, both as characters and as caught Pokemon.
Don't be disruptive. You can have loud, obnoxious characters that cut people off in the middle of conversations, but don't break the flow of the RP.
Pokemon choice will be restricted to an extent. Preferably, you'll take the Type Quiz in-character and make them a Pokemon of that type (assuming said character is a Pokemon.) You can also have the group make a list of Pokemon they think fit you, and you can choose. You can also let people just plain choose for you.
You don't have to strictly follow canon, but any deviation should have a solid explanation. Better, more interesting explanations lead to more leeway.
As for setting, we're going with the Reborn region, probably set in the future. I like the sound of the "post-apocalyptic" type story, so setting it later will fit better. I'll let people have whatever kind of backstory they want, unless it gets too Sue-ish (a judgement made by the group). This includes the Mystery Dungeon-type (was human, turned into Pokemon). I'll prepare a story outline for anyone that wants one, unless Acqui comes back with her ideas, in which case the story will be different anyway.