I actually would...in a story I'm writing, my two characters from Sky make cameos with Wigglytuff's Guild (although Bidoof has the most time out of them) and Zapklaw (Player character, he's a Luxray) and Friendrita (Lousy name, I know, but she's a Meganium), I'm planning something to happen near the ending...
Anyways, it would be epic if it could happen in-game. XD
Egg groups would be the only problem there, but then again, they're often ignored in roleplays etc., so...