I know this is more peppy's area, but as far as moves go, I say give her a basic set of defaults and give people a utility to create their own per song or whatever. Like MikuMikuDance. so far Osu! has been really customizable, and i think it'd be fun to have do a unique set of dance moves for a song.
A utility would take a load off Pippi's Animator, which I'm assuming is Loginer, cause then he'd only have to come up with the defaults. Anyways, I'll shut up now, as i'm sure I've just pissed several people off. lol.
exaggerated karate dance style sounds like it could be fun.