Yeah, there'll be a whole miniquest with the judges with Gabranth as its main boss... You'd have to play through the whole quest with Vaan, whom you would have unlocked by beating the game. He would SUCK and the goal of the miniquest would be to be beaten BY Gabby! Then all the judges would be available to play with and, additionally, you would unlock Basch!
Dammit! How did you know?!
Dont tell anyone but,

Spoiler: So will Darth Vader
OMG!!! You know that too! How annoying, that was gonna be MY big suprise!




But jokes aside, I'll tell you why Gabranth will be in it:

- In the last Famitsu interview it was confirmed that the last remaining unrevealed character would be from ffxii.

- In one of the Dissidia events a long time ago, there was a picture of Judge Gabranth up on the wall, so my sources inform me.