Looks like Kuja is there too.

I'm going to guess it's a Crash Bash style game where Zidane enters a tournament filled with wacky mini games and keraaaazy opponents. Why? The prize is an artifact which can bring the dead back to life, and Zidane and the gang miss Vivi. However, that naughty Kuja has entered too because he misses Brahne or Garland or his dragon or something. But soon, the two former foes realise that horned guy is more evil than he first appeared, and they must team up to defeat him in a chocobo racing minigame or else the world is DOOMED!

EDIT: Uh-oh, looks like somebody beat Jowy to it. Merge-time.

I think for the time being we'll keep it in General FF until it is confirmed one way or another that it is directly to do with FFIX, because it doesn't specifically say "IX" in the title so yeah.