There is a game that might offer a template. Iron Phoenix, which is supposedly going to be a very fun multiplayer game for XBOX, allows for up to sixteen players to get going at once, each wielding and then switching a variety of weapons, and partnering up for a variety of cool combo attacks.
While this game supposedly plays like a really fast multiplayer version of Dynasty Warriors, it could be modified to support a variety of Capcom or X-Men, or whatever style players, with the Grooves potentially replacing the variety of weapon styles that fits in Iron Phoenix (although, I really dig the idea of my character switching from style to style at my whim).
And since Sammy Studios owns the rights to Iron Phoenix, it's at least somewhat within the realm of possibilities.