Joe Louis had weaknesses such as starting slowly, or getting knocked down early, weighing under 200lb, vulnerable to the right hand, could be out boxed by very good fighters, which could have been exploited by other great fighters but he was a great champion nonetheless.

Don't let me get started on Rocky Marciano.

Ali would have beaten both the fact that he beat 3 great fighter in their primes in his era just cements the argument.