I've released the RPG rules I've written so far, up to character creation. They're available on the forum. Here's an example character sheet.

Rainbow, female Kecleon. A wild Pokémon that follows a group of trainers wherever they go.

Moves:
1 Attract attention
2 Frame someone else
3 Mimic others
4 Invisibility

Traits:
1 I get others into trouble
2 I like to get yelled at
3 I don't want others to get hurt
4 I'm independent
5 Nobody pays attention to me

(Rainbow will always remain a wild Pokémon. The group of trainers will never lose her.)

Yes, that's it. I thought her up in a couple of minutes. She's not created in the context of a show, but you could imagine her following Ash & Co. in the anime.