Ali had one of the best chins ever, maybe the best absolute. Never KOed, with Holmes more than a TKO it was a retire in a fight where he clearly fought sicko and damaged. Though..make a list of fighters who iyo could KO Ali.
Tyson had the power but also the skill which Foreman and Liston didnt have. I also felt he punched harder than Frazier.
The thing is, any historical heavyweight worth ranking in the top tier of contenders (Liston, Foreman, Frazier) all did actually fight him and weren't able to, so........
Liston and Foreman did not land proper hard head shots on him, where they could put all there body weight behind the punch.
Frazier was close to stopping him, but I think we saw his absolute peak. LL might have a chance. I'll add Bowe's name for a wild card.
Has Wilder some chance ? I think given that Ali hold several bombs from Shavers he should survive Wilder more or less like Fury. Or not?
Big heavies with little output per round aren't going to trouble him. It's the smaller fighters with B+ level power who will attack his body non stop for 15 rounds who are the most likeliest to stop him. Fighters like Frazier and Marciano come to mind. It's still very unlikely but can't see the likes of Wilder or Lewis stopping him.