>>23501316
Having assists made him a borderline unstoppable force in vanilla, and UMvC3 let him cancel anything into fully-charged Z Buster and Sougenmu so you could forgo assists. One of his attacks in Project X Zone references his lightning loop infinite where you loop the OTG, fully charged buster, 3x light lightning, and Sougenmu until you run out of meter.

He was absolutely busted in vanilla, but other characters like Dante, Wesker, Sentinel, Wolverine, Phoenix, and Wesker were more busted so nobody paid attention to ultra high execution Zero until they had to in UMvC3 when he escaped nerfs because nobody was good enough to use him yet.