Boy, I thought the Tournament Fighter games were alright, especially the SNES version.
I hope this new game features a fighting system similar to Smash Bros., because that would make for a great party game. Viewtiful Joe made it work (sort of), so it can work for the TMNT. I really hope the developers make an effort to reflect the entire colorful history of the franchise in the character roster. In my opinion, nothing beats the original Eastman & Laird treatment, but the next-best thing is the recent animated series in terms of art direction. Characters I'd like to see:
Karai/Lady Shredder (transforms like Samus in Smash Bros.?)
Armaggon (from the Archie Adventures Series, was also in Tournament Fighters)
Null (also from the Archie series)
Leatherhead (the original Leatherhead, please, not the cajun bastardization)
Umeko ("Ninjara" from the Archie series)
Zog (a Triceraton soldier from the new animated series)
Other suggestions?