Quote Originally Posted by Ashley Schovitz View Post
Onslaught should be up there too since he's as equally as powerful as either two since it took the entire Marvel universe to defeat him, but a fight with all three would destroy existence.
Onslaught isn't even close to Galactus in power. For that matter, neither is Ultimecia seeing as how she lost to your party in FF8. Galactus already survived the destruction of one Universe, the rebirth of that Universe as the Marvel Universe, and possesses more power than any mere mortal and even many of the cosmic level entities in the Marvel Universe. Even if Ultimecia can absorb the Universe, she'd have to do it before Galactus killed her, which give her track record I wouldn't bet on.