Which character in any anime do you think has had the biggest power boost in one move (except DBZ because that's pretty damn obvious). It has to be ONE power boost. If a character absorbs some power, then 4 minutes later he absorbs some more, and then he absorbs more later on, that's not a power boost it's too constant. It has to be sudden, like Bankai. And put why. I think either Gash from Konijiki no Gash Bell manga during the Clear Arc because Makoto Raiku decided to be a cheap ass and give him 4 new super powerful spells at once. Mayyybe Clear Note, but he was already unfairly strong before his power ups so it wouldn't count. Or Megaman Greiga Beast out. He went from a weak-ass to a godmoding psycho in 3 seconds.