Ifrit
Fire Elemental
Ifrit is a strong GF picked up early on in the game. He resembles a large ogre and uses the element fire. This makes him strong against ice enemies but weak against fire. His Mad Rush ability can seriously bolster your party early on and his strength bonus ability can create a strong fighter out of whoever he is junctioned to.
Found in the Fire Cavern. To gain him you just have to beat him. With Quistis on your side and plenty of ice spells he shouldn't prove too hard