I really don't think I'd pick the 1980 Muhammad Ali to beat any of the top tier heavyweights of the time, which Mike Weaver certainly was and then some. I think Hercules would chase him down and batter him on the ropes, corners, etc, and Ali no longer had the mobility to evade him.. About the only ones Muhammad might have taken at that point were the fringe guys like Scott Ledoux, Tex Cobb, Marty Monroe, Stan Ward, etc, but even some of those might have given him some problems at that junction.
I don't see Mike Weaver chasing down anyone. Weaver was a counterpuncher for the most part. He'd stand there or slowly shuffle forward and wait for you to punch. Then he'd cover up and counter. Sometimes, he'd cover up and wouldn't counter. (It cost him the first Dokes fight.) That's why he didn't win a lot of decisions. If he could catch you after you threw your three, four or five punches, great. But he wasn't a guy who chased and battered people until they had no mobility left. If Weaver's opponents had no mobility left, it was usually because they threw so many punches they'd gotten tired. I'm not staunchly behind Ali winning. I just don't think we saw a fit Ali in 1980. We saw a guy abusing drugs who the Nevada Commission let fight (even though his body was full of pills he admitted he was taking by the handful) because they didn't want to miss out on the payday. Today, Ali would've failed every drug test given from the moment his camp opened. So, it's difficult to tell. But in 1979, with no training at all, in an exhibition with Alzado (who was considered the strongest man in the NFL at the time and was himself roided to the gills) Ali handled himself just fine. He was punching strong. He could take punches. He could turn it on and off. Two and half years later against Berbick he was shot. And even then he looked better than he did against Holmes. Holmes beat Ali because Holmes was a sharp boxer on his game throwing non-stop. Weaver didn't fight like that. Weaver covered up and countered mainly. I think Ali would've been far ahead entering the final five rounds. Whether Weaver could stop him would've determined who won. Tate and Coetzee were far easier to stop than Ali ever was. So I don't think Weaver would've. That's why I'd go with Ali.
Even a prime Holmes had a helluva time keeping Weaver off him and at one point looked as though he was going to lose that fight.. Tate got knocked out around that time and Coetzee was stopped.. All these guys were better in 1979-1980 than Ali who was inactive, out of shape, and in declining health. If Muhammad fought Weaver at that time he'd take a helacious beating from a guy who had more power than the two men ( Holmes and Berbick )who thrashed him.
Holmes was sick as a dog for that fight. His purse was next to nothing. And it was a tuneup against an 18-9 opponent before his big fight with his top contender Shavers in the fall. Despite all that, Holmes was way ahead on the cards and stopped Weaver. Weaver didn't have more power than Holmes. Holmes flattened Weaver with one shot. Weaver needed the ropes to get to his feet. Holmes stopped Weaver twice. Holmes and Weaver fought nothing at all alike. Holmes was a 6'3" aggressive boxer/puncher who dominated with the jab and worked off it. Weaver was a counterpuncher who let everyone lead and he tried to block shots and counter with power punches. Weaver was two inches shorter than Holmes and Ali. He had a shorter reach than Holmes and Ali. He would let Ali lead and counter with power punches. Weaver wasn't going to win a decision over Ali coming off Ali's win over Spinks. A lot of guys outboxed Weaver. Leroy Jones. Stan Ward. Duane Bobick. Rodney Bobick. John Tate. You didn't need to be anything special to outbox Weaver. Hell, Bill Sharkey nearly did it.
Well using that logic, take a harder look at Ali. The 1978 guy. You know, the one that had to go 15 with Evangelista. How many other guys would have to go that long to beat that guy? Did Holmes lose 1 minute of his fight to the guy? Then Ali loses to a novice fighter in Leon Spinks. Who got the title fight as a result of a draw against Scott Ledoux. Hardly the best of credentials there. Then Ali beats Spinks in a dreary rematch. Couldn't ko him, a 15 rounder. How'd Leon do when he fought his next fight against a heavy---oh yeah he didn't make it through the first. Did Ali win 1 minute of a round against Holmes? The Ali in that timeframe is just not that good.
Throw the Holmes result out. Ali was the victim of bad doctoring. Ali gave a good performance against a young, virile Trevor Berbick, who was just coming off giving Holmes a run for his money. A better training camp and Ali would have won that fight. I see Ali making a strong run through the 1980's with Weaver being not the most impressive pelt he takes.
Throw the Holmes fight result out because why---he lost badly? Both Ali and his camp claimed he was in terrific shape for the fight. They were ready. And they went through that Mayo clinic stuff before the fight. Come fight night he was in a bout wh a young talented undefeated fighter in top shape with tools. It'd been how many years since he had faced that type of opposition? It changes a lot of things when the other guy has the big advantage in reflexes. So he lost. And badly. But he could have postponed the bout. Or cancelled it. He'd been delaying and talking about proposed fights for years. Excuses after the fight & lots of guys have them. Arum would have put Ali in the ring with Weaver in a heartbeat if the Ali braintrust wanted it badly. He sure didn't ever show much of an allegiance to Weaver at anytime. And breaking a contract with King just means those two end up in court again. But there were pre-fight options available and different roads to take.
Lots of fighters in 1978 to 1981 would have defeated Muhammad Ali. I wouldn't count on him beating Scott LeDoux.
The "one shot" that Holmes decked Weaver with was a huge right upper cut ( something Ali didn't have ) while Hercules had him trapped in a corner and was pegging him systematically.. This was also in the 11th round of what was already a grueling fight. If Weaver could counter the sharp fresh Jab of Holmes and land regularly, he could certainly do that to a 38 year old, two year retired diminished Muhammad Ali. Mike was in excellent condition. Was capable of going 15 rounds and still scoring knockouts at the end of it.. He was going toe to toe with just about every top heavyweight at the time and beating most of them.. And if Holmes performance was due to being "sick" or "unmotivated" then he must have been under the weather for the rest of the 1980's because he sure as hell never gave Hercules a rematch.
Ali was a sitting duck, no power ,no reflexes , no movement and his hand speed was long gone. After Mike realizes Ali has nothing Weaver might knock him completely out.