Mash and Saitama are both total powerhouses who can destroy most opponents with a single punch. In a way you could say that Mash is probably based on Saitama but in this case the copy cannot defeat the original. Saitama is much too powerful here and his stats around the board are just way too impressive. Mash’s punches probably wouldn’t even do much if any damage to the guy. Saitama is just too broken to lose at this point. Saitama wins.