Try to get Squall & Zell/Irvine's STR to 200~255 (if not cast Meltdown to Ultima). Try to summon Cerberus. If not, just waste Triple. If Quistis is in the party, use Mighty Guard once in a while. Also use her to Double/Triple Cast Curaga/Ultima (depends on the situation). If you have all the guys, Squall should use Renzokuken, Zell w/ Armageddon Fist combo and Irvine with AP/Quick shot (Quick shot may deal 25k worth of dmg depending on his Str). If someone dies, cast Life (not Full-Life but make sure your HP doesn't drop below 2000 else you're dead meat). If you still can't beat him then use Selphie's The End trick (Playstation only).