Not necessarily sitting champions, just fighters who held belts at one time or another. Roberto Duran beat: Ernesto Marcel (feather) Hiroshi Kobayashi (junior light) Ken Buchanan, plus Guts Ishimatsu and Esteban DeJesus (lightweight) Saoul Mamby (junior welter) Ray Leonard (welter, middle, super middle, light heavy) Davey Moore (junior middle) That’s six classes he defeated former, current or future world champions in … and that doesn’t count Iran Barkley because middleweight is redundant. Not to mention he beat Carlos Mendoza, who fought for the title at 122. Anyone exceed, equal or come close to that?
Pretty sure it's Mayweather, his win over Pac alone is a cheat code with him crossing 8 divisions. Add Canelo (160-175) and that's 11.
