Ifrit
Absorb Fire
Weak against Ice, Water

This is fairly easy; have Quistis summon Shiva while Squall casts 
Blizzard spells. (They'll do a little more damage than Water does.) The 
timer stops after you win, so don't worry about not having time to get 
out afterwards. When you win, you'll get 20 AP, a bunch of G-Returners, 
the Ifrit Card, and the Ifrit GF.