MAME for Wii don't really support alot of modern games, but TMNT 1 and 2 both work on it. And Wii's are really easy to mod.
Otherwise, the only legit way to get it is to by TMNT 2: Battle Nexus for gamecube and unlock it
http://www.gamefaqs.com/gamecube/920...e-nexus/cheats
It's annoying to have to play through another game just to unlock what you want tho. It does work on some wiis tho.