Depends. Do you consider Mike Tyson as a smaller guy than Holyfield ? Or vice versa ? Because those 2 are the smallest guys I'd favor to beat Joshua, then you got Ali, Foreman, Holmes, prime Povetkin and Ray Mercer on a good day Sub 200 pounders like Marciano or Walcott are not beating Anthony Joshua just because Usyk beat him. Usyk was 6'3, 220lb+ Take the nostalgia glasses off
Joe Louis in his prime was about 6’1” and his prime weight ranged from like 199-210. I would pick him to beat Joshua.
Andy Ruiz if he went on a diet and lost the fat he carried into the ring with AJ. I have no idea what weight that would leave him but the first fight when he weighed 260 odd, he was obese. As I say, I don't know what he'd have weighed if he was lean so I'm not stating a fact before I get put in my place, but it wouldn't surprise me if he could have got down to less than 200. He's not that tall and that was a lot of fat. Other than that, quite a few. Based on what I've read rather than seen, Dempsey. Walcott. Bonavena. There are loads imo. AJ's just not that good.
Joe Louis for sure, he was around 205 lbs at his best. Someone smaller than him? I don't know, maybe Dempsey? Not sure, but he'd have a chance. Or maybe some smaller technician who could run for the whole fight and outslick him?
Frazier and Louis definitely. Charles, Walcott or Tunney wouldn't massively surprise me neither. Dempsey, Marciano. If AJ. Doesn't get them out early, they probably stop him late on. And I don't think he gets them out early.
Archie Moore handled a fair assortment of big lumps using guile and power. At around 8 inches shorter, I reckon Arch would have been smacking his lips at such a large target. It was the livelier, smaller heavies like Charles and Patterson that caused him more trouble.
Already mentioned but Louis. I would have favoured him even before the Usyk fight now just even more so. While I think Charles, Walcott and Dempsey all have a shot not sure if i would favour them more lively underdogs.