60s Muhammad Ali vs Joe Louis- Ali gets dropped, but comes back and puts on a dazzling display of boxing speed and agility. Though Louis is throwing astonishing combinations Ali beats him to the punch too often. Ali UD Joe Frazier vs Evander Holyfield- Holy really roughs up Joe, but succumbs via TKO 10 Mike Tyson vs Riddick Bowe- Bowe COULD win, but he'd have to be mega motivated Either Bowe by late round ko or Mike by UD. George Foreman vs Larry Holmes- Larry boxes the hell out of George, gets a little cockt and gets dropped hard. Larry comes ripping back and overwhelms a gassed out Foreman in 10. Lennox Lewis vs Riddick Bowe- 1992 Bowe stops Lewis in 6, any other Bowe gets Lennnox's foot stuck in his ass in around 8. Rocky Marciano vs Jack Dempsey- Rocky lands the crushing blow in 9. Sonny Liston vs George Foreman- Foreman had more heart. So he'd win in 6, but Liston would put a horrible hurt Joe Louis vs Joe Frazier- Louis would be hell for Joe early on, knocking him down badly at least once and nearly stopping him. Frazier smothers the hell out of Joe from that point on, scoring a terrifying knockdown later in the fight. Louis is staggering badly by the 15th round. Both men are horribly disfigured at the end. Frazier MD 15.
I think Marciano would win against Dempsey. If Schmeling is in good shape, I think he can beat Dempsey and Tunney. I wouldn't be surprised, if Vitali Klitschko would beat Foreman and Tyson. At least, I slightly favour him against Foreman. Louis vs. Liston would be very interesting. it could go either way, but I tend to Louis. Louis vs. Foreman would be a great fight too. I agree with the rest.
Think you underrate Dempsey a tad. I give Schmeling no chance against Toledo Dempsey. I also see Marciano blown out to tbh. Dempsey is bigger, faster, stronger, hits harder (debatable), better defensively, more well rounded, etc. Only advantage I can give Marciano is stamina tbh.
So far, I am really not that impressed with Dempsey. Schmeling was a very clever counterboxer and he could beat Louis. I think Marciano had defeated better opponents and would be to powerful and persistent for Dempsey over 15 rounds. I favour Marciano, but we will never know.