Got a cool idea that could work.. And im not trying to rip off SSF2's handy book at all.
Basically, in Mega Man 6: You had 2 extra rush suits in the game which were the Rush Power Adapter and the Rush Jet Adapter. In Mega Man 7, you had the Super Mega Man Adapter.
Maybe for a Final Smash: We could get a fully playable Super Mega Man. Unlike SSF2's version where all he does is Fly and punch, Mega Man will achieve a new moveset and use his power and jet adapter abilities as his specials. Instead of punches and kicks, Super Mega Man uses Robot Master weapons as his normal/smash/grab/air moveset.
And we could leave the MVC Megaman as is but with a minor weapon select change and some tweaks/new moves. It would have a sense of players feeling alot more powerful than they were and dominate the battlefield in total destruction: Basically the purpose of a Final Smash, No?
Good idea or no?