Say, I was thinking about it and I just realized the fight between Little Mac and Ridley would actually be unfairly tilted in Little Mac's favor, since Little Mac's specialty is reading tells, dodging, then counter-attacking. Ridley's nothing if not a show-boater, given that most of his attacks are preceded by him either posing, or roaring loudly, he telegraphs constantly. Given his fast dodging and his experience fighting enemies much larger than himself, I'd really have to give this fight to Little Mac. Ridley may have size and strength on his side, but that's more or less the standard set-up of every Punch-Out fight, Little Mac vs someone bigger and stronger.
Of course that's not to say Ridley would be a bad character or fighter, but just that in that particular fight, it'd be more in Little Mac's favor.