wtf? Lewis outboxed prime Tua badly, very badly. Did Tua even win one round? Lewis always would beat Tyson. They sparred when both were still amateurs and Lewis figured Tyson out. Mike never changed his style and Lewis had the plan to beat this style. Ibeabuchi is becoming very overrated. Who has he beaten to suggest he could hang in there with Lewis? Foreman and Liston against Lewis would be two great match-ups but I would favour Lewis against both, only slightly against Liston though. Ali is something different. I think his speed would trouble Lewis but I also think Lewis´ jab would trouble Ali. 50/50 type of fight.
I think Dempsey would beat Ali. Dempsey had pretty fast feets and hands as well, not as fast as Ali but still. Ali had trouble slower and far more predictable swarmer in Frazier. Dempsey just does everything a bit better than Frazier with perhaps the sole exception of Frazier´s superior stamina. Joe Louis was outboxed by Conn during a good part in their time. Ali was even faster on his feat and his lead right hand would land pretty often. Louis would be dangerous throughout the fight and in a trilogy I think Louis would win one fight but I take Ali here. Marciano was the most unorthodox of the hw swarmers - he even wasn´t one for his whole career. When they did the the movie for this computer superfight in the 60s, Ali said he was surprised how hard to hit Marciano is. And this was a retired, far far past his prime Marciano. The rock´s workrate, unorthodox style and pressure would trouble Ali badly. Either Rocky by UD or Ali on cuts. Mike would have lost the fight when the contract is made. To win Ali wouldn´t even need to set a foot into the ring. Tyson would crumble under Ali´s mental pressure. We don´t need to talk about the actuall fight because Tyson wouldn´t really be able to deliver anything he is able to normally. Ali has a very good chance to beat Lewis. His speed, jab, lead right and angles would pose many many problems for Lewis. But then Lewis himself had a very good jab and was pretty fast for his size. He also had a big size advantage and the power advantage. I can see Lewis beating Ali too and it would be an even fight through the first six rounds but Ali would make Lewis chase him and work hard and so Lewis´ stamina fails him and Ali wins on points or late stoppage. All in all, Ali would come out 3-2 against these 5. Pretty good imo.
Young Ali would have been way too fast for Lewis. Prime Dempsey would have given Ali a good fight, with Ali winning decision or late stoppage.