Quote Originally Posted by Behold the Void
Gunner is Moogle, Juggler is Moogle, Sniper is Viera, Defender is Banga.

I believe Juggler requires two Thief abilities, Sniper requires two Archer abilities, Gunner requires two Mog Knight abilities and Defender requires two... well, either Warrior or Monk abilities. I think it's Monk.
almost its warrior