I might get beat up on this but Tyson greatest gift wasn't his power but his hand speed...Mike was always soft to the midsection(meaning fragile, not out of shape) and his footwork needed constant supervision by Cus and Kevin...when his footwork was on, and he used angles combined with his handspeed this made him a freak in the heavyweight division...Cus had him fighting every month, training every day so his reactions would become instinct...during his downfall, when he started pausing before throwing was because he was "thinking" and this left him open for abuse...Mike had to overcome being a short heavy it was the quickness and inside angles that nullified the hieght dis-advantage...when he became the "slugger" that appeared against Rudduck it was the end...

Cus' style was one that relied on quickness and aggressiveness, never taking a step backwards...either he forgot that post Rooney or never really understood it...Mike also always had an absolutely granite chin which also masked his decline a bit...

Prime Ali vs Tyson I'd have to go with Ali, only because Ali had the ability to adapt which Mike never really showed....