So basically the game is working fine, running at 60fps and the only issue I'm having is with Sonic. I get a weird texture like thing coming off him and he's the only character/thing in the game that I've seen with this problem. I have no idea how to fix it, could you help?
I haven't confirmed it, my bad.
I don't get the same issue in Ishiiruka (specifically Faster Melee 5.9 Beta, the latest version), have you verified that the dump isn't corrupted? Dual-layer games like Brawl are a pain to dump, I don't know how many times I had to dump it before I got a working dump.
I think this is a cached display list issue, reminds me of old bugs related to that. If Ishiiruka has an option like that, I suggest you turn it off. Anyway, this doesn't happen in master. If you need more assistance go ask in the Ishiiruka thread.