The Tucker who stopped Douglas fights the Charles that decisioned Louis. Tucker was bigger, but wasn't exactly a puncher.
The thing with Charles is he fought in the smallest era of HW and beat the version of Louis who'd lost his power. Tucker is better and bigger than say a Nino Valdes.
Tony Tucker was great and underrated. When he became champion, I was going through a period of retracting from boxing because my fanaticism had reached legendary levels. His fight with Mike Tyson is what brought me back to watching boxing. Because I was at an advanced level academically, I was recommended by my teachers in junior High to go to a High School for higher-achieving students that attended on Saturdays only. And I was placed in a class that only had 6 girls total. me and five other girls. I remember talking to my girl-friends that day about the fight, that even as I was stepping back, that was the ONE fight I really wanted to watch. I never looked back and never deconstructed as a fan again. But he was not THAT great. Anyone who can outbox Archie Moore outboxes Tony Tucker IMO.
If Charles is able to bulk up appropriately like Michael Spinks did, I’d pick him otherwise Tucker might just be a bit too big against the 182lbs or so Charles. But with modern nutrition and whatever else, Charles should take it.
I’d pick Tucker to handily defeat that version of Louis and any fighter that was at world level who could get on their toes. I think that version of Louis was probably around slightly worse than a Jerry Quarry, but still better than a Leon Spinks, maybe around James ‘Bonecrusher’ Smith level, but slightly better.