Capcom announced and showed during a Marvel games panel at New York Comic-Con that Galactus is a playable character in Ultimate Marvel vs. Capcom 3.

Basically, Galactus inhabits the right side of the screen from the waist up and blasts, crushes, and pounds his enemies. He had no health bar and seemed to take no damage. The panel described this as its own mode.

So much for fair fights!

(via IGN)