Oh wait, I forgot about Sora! He's probably a viable answer, although technically he would have been eligible for the first contest because of the Japanese release and all. Still would have a chance at beating all those mentioned so far, and he probably was the strongest character ever from the last 10 years, even if he's dropped off currently.
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My bracket wasn't good enough to beat SuperNiceDog's in the GameFAQS Rivalry Rumble. Congrats!
This is Yesmar.