This save has all ultimate weapons, the best magics in the game for junctioning, Auto Protect, Auto Shell, Auto Haste. The save is right in front of Ultimecia's Castle, and Omega is waiting to be popped. I recommend taking Squall, Rinoa and Quistis to the fountain right before the pop spot, then switching to the second party, and heading up the stairs and to the right to ring the bell.
Omega's first move is to cast LvL 5 Death on everyone, which is why I have 100 Deaths junctioned to Status Defense. After this initial spell, Omega follows this attack pattern:
Meteor megalixir after this to survive next attack Megiddo Flame megalixir after this, Aura on Squall, Renzokuken Gravija megalixir after this, Defend with Squall/Quistis Terra Break Full Life on Rinoa if necessary Ultima all three chuckle/fistbump Light Pillar Full Life whoever got hit
Squall's job is to use Renzokuken as often as possible, and hope for a few Lionheart finishing moves. He has to use Defend right before Terra Break, and he may have to use Full Life on Rinoa, or pop a megalixir as needed. Rinoa and Quistis will be mostly using megalixirs, and casting Aura on Squall. At times it is necessary for one of them to use up a turn, in order to allow Squall to cycle through his own turn alone to bring up Renzokuken. I use Defend or Regen when this happens. It can be a long fight if you're not lucky enough to see Lionheart a few times, but it is an easy fight if you're always prepared for Omega's next attack.