Tallying up feats:

-Ultimecia can make a monster real but of course said monster can't beat some teenagers with no feats.

-defeated four times by SeeD.

Now Kuja...

-laughed off a direct attack from Bahamut who is stronger than Odin who can deliver Atomic Bomb-level destruction.

-disposed of the party in one attack.

-destroyed a planet.

-destroyed the party once again.

Seems obvious Trance Kuja would won her as none of the FFVIII party can destroy a planet and they beat her ass multiple times.