This is hard to measure because the only way to tell if a fighter smokes weed would be if he tests positive for it after his bout. However, if you test positive for Weed which is considered a banned substance you'll get suspended.
With that being said its nearly impossible to tell if a fighter had a successful career smoking weed because he'd probably be trying to avoid testing positive. The only way to figure this out would be to actually ask a fighter or test them when they're not actively training for a fight.
Frank Bruno smoked weed and I think Nigel Benn did to, however I don't know if they did it whilst they were actually in training for a fight, probably not. My advice would be avoid weed if you want to be successful in any sport.
He's not great but Julio Cesar Chavez Jr.
