GFs: Quezacotl, Brothers, Pandemona, Cerberus, Bahamut
Abilities: Auto-Haste, Initiative, HP+80%, Str+60%
Magic: Meltdown (at least 2), Aura (at least 4), Ultima (as many as you can get, preferably 100), Triple (try for 100), Blizaga (100), Regen (100) and 100 of as many strong spells as you can get. (See spells section to see where to get them.)
Junction
Regen to HP
Ultima to Spd
Triple to Str
Blizaga to Elem-Atk
and all powerful spells to Vit and Spr
Any Quakes or Meteors to Elem-Def (try to get a green star next to the element icon)
Character 2 (Was my Zell)
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GFs: Cactuar, Ifrit
Abilities: Initiative, Kamikaze, HP+x% (as much as you have)
Magic: Regen and almost anything else
Junction
Regen to HP
as much as you can to Str and Vit (if you have other GFs also equipped)
Character 3 (Was my Selphie)
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GFs: Leviathan, Shiva, Alexander
Abilities: Recover, Revive, Draw, HP+x% (as much as you can swing)
Magic: Regen (100) and as much of anything else strong you can get
Junction
Regen to HP
Any quakes and meteors not on Squall to Elem-Def
Now begin the fight.
Step 1.
Have Character 2 do kamikaze. This should cause almost 50,000 damage to Ultima. Have Squall cast meltdown and character 3 draw Eden.
Step 2.
Have Squall cast Aura on himself. Or, if Meltdown didn't work, have him cast it again. Character 3 should heal Squall if he took any damage, or stay on stand-by.
Step 3.
Keep pressing *circle* on Squall until he gets a limit break. Use Renzokuken to Ultima. Each hit should do over 8000! Character 3 should heal if still alive. Character 3 is used as a target for light pillar, Ultima's cheapest attack.
Step 4.
Have Squall keep using his limit break until Aura wears off or Ultima dies. For me, Ultima realized he was outclassed after 2 Renzokukens, a Fated Circle and a Blasting Zone. It was a shame that I didn't get Lion Heart.
Step 5.
Have fun kicking the #$%^& out of Ultima, and stay tuned to see if I can actually beat Omega. He better watch out for the "Weapon Hunter"!