Win.
Anyway, I think that the argument "Kuja destroyed a planet" to justify Kuja winning Round 2 isn't sound, because Round 2 Kefka was limited by the storyline; there is only one planet, and destroying it would make him succeed, and the villain can never win.He did beat the world to within an inch of its life, and we can safely assume he could've destroyed it completely. The only reason he didn't was because he had no desire to. That said, I still think Kuja would win Round 2, because Kefka can't really control all magic in the world, since then you wouldn't be able to use magic against him in the final battle of FFVI. And Kuja's Ultima is just too strong.