How easily does Prime Muhammad Ali deal with his toughest opponents? (Below)

Might still lose to Norton and Frazier. Especially Norton. Norton was just his kryptonite.

Stops Young, Foreman, Lyle, and Spinks.

 

Ken Norton: It's a style matchup, and would be just as hard as the actual fights. I think it would most likely be very visually similar to the 2nd fight.
Joe Frazier: Again, probably a visual similar to the rematch, one thing I think should be considered is a 60s Ali did not have the clinching or inside brawling experience a 70s Ali had experience in. It is very possible a 60's Ali cannot dance the full 15, and is too inexperienced in the clinch to handle a FOTC Frazier.
Jimmy Young: I would go with Ali by a wide decision, often taunting and making a show out of Jimmy. A grotesquely out-of-shape, far from prime, and 34 year old Ali was not completely outmatched by a prime Young (granted it was one of the worst fights I've ever seen in my life).
George Foreman: I would go with Ali late TKO. I actually think Muhammad gets damaged quite badly in the mid-rounds, prime Ali did not have the experience and IQ he used in Zaire.
Ron Lyle: Ali late rounds TKO, wide decision at most.
Leon Spinks: Ali via TKO, Spinks was lucky to catch Muhammad in the stage he was in.

 

The only one I think the 1965-67 Ali would be underdog against would be Frazier. He would always have had to lose once to Frazier to appreciate his quality & work out how to best him IMO.

Norton is still a difficult fight, but the speed is troublesome enough to keep Norton from winning eight rounds. Something like 8-1-6 Ali seems reasonable. He’d never have an easy time but he was significantly better in 1967 than he was in 1973, if not necessarily smarter.

Foreman is interesting. I give him a chance to upset the apple cart here - albeit a small one. He will not be coming in under-done & with a bad shoulder & knee, ala Liston, & since Foreman is presumably the challenger here, he’ll be the hungrier man. It’s possible his ring-cutting skills & massive power could spring an upset, but you would bank on Ali’s speed & endurance being too much for him I think.

Lyle gave a great account of himself against an older Ali, but he had trouble with speedsters & manoeuvrable foes - none embody these qualities better than Ali. I think he staggers & stops Lyle very late, but it’s nowhere near as competitive as their actual fight.

Spinks’ corner would pull him out after nine or ten rounds. Totally overmatched, he wouldn’t win a round.