Sonic gave Kirby an easy 55/45 last year, and that's clearly a more accurate representation of their true strengths than the Kirby upset. Meta-Knight may be stronger than Robotnik, but the Sonic/Robotnik rivalry is pretty iconic. I know noms are a dubious metric to judge anything, but I'm surprised Robotnik even outgunned Knuckles and Shadow to get in. I think that alone is testament to the quality of the rivalry. Also, Kirby and MK's rivalry is probably weak here. I bet MK gets the lion's share of his strength from his awesome design and Brawl. The Kirby games are so damn weak on this site that the rivalry can't mean much to most people.
--
Yoblazer: http://oi52.tinypic.com/ad21i1.jpg
Watch and you'll see... someday I'll be... part of your world!