I have had this wierd issue for a while now. I use to think it was another Wii issue, like how my Battlefield stage will not play music, no matter who's Brawl disc I may use. Either way, I can not use the Pokemon trainer as a team for some strange reason. I go into battle and if I try to switch Pokemon, the game freezes. But when I was using Project M I was able to use the Pokemon Trainer perfectly. Any one know what the problem might be?
It might have something to do with the Pokemon themselves. First off, all 3 Pokemon MUST have both a .PAC and .PCS file since they are 'transforming' characters. Same thing for the Trainer itself. If it doesn't work, try re-creating it via BrawlBox (FitPokeZenigame00.pac/pcs) for example. Some hacks in the vault does make the Wii crash sometimes if not used properly, though I don't remember which ones, so it's better re-creating these files... As for Battlefield, check in 'My Music' and see if all music is disabled or not. Hope I helped