The party mode characters are in some funky file I don't remember the name of. I don't know of any way to decompile that file but Random Talking Bush helped out with that a while back (five years ago, wow) so here's what was contained in that (the .pvr files are textures, those are easy enough to convert):
https://www.mediafire.com/file/v3q312e94...yChars.zip
The .GNO files have every bone for every character contained in them so you'll have to go through and find which bones are actually assigned to the model it is you're trying to pose. Some characters, such as Tails as Ali Baba, don't have an in game model. Knuckles's character Sinbad does, but it's just an object in the level it appears in and isn't rigged, just a pre-posed model. You can find more here: https://www.models-resource.com/wii/soni...cretrings/
I hope all of that helped!
https://www.mediafire.com/file/v3q312e94...yChars.zip
The .GNO files have every bone for every character contained in them so you'll have to go through and find which bones are actually assigned to the model it is you're trying to pose. Some characters, such as Tails as Ali Baba, don't have an in game model. Knuckles's character Sinbad does, but it's just an object in the level it appears in and isn't rigged, just a pre-posed model. You can find more here: https://www.models-resource.com/wii/soni...cretrings/
I hope all of that helped!