I will say this much though, as far as defense is concerned these fighters now a days don't take nearly as many power punches as a lot of 90s fighters did, especially the heavyweights.
Anthony Joshua is more defensively responsible than ANY 90s heavyweight when he actually just uses his length and fights big, and in the 90s he would easily be the biggest heavyweight, bigger than Lewis or Bowe. Tyson Fury honestly that size difference and his ability to be crafty and move instead of being a big slow behemoth but can if he needs to as he just proved, he is a matchup nightmare bruh. I don't know I can see how this era of heavyweights would have success back then, even if a lot of them back then had more technical skills offensively.