I just consulted Sage Garlyle's book of success.
Omega has a cycle like most superbosses do (except Ozma from FFIX, I think?)
1 - Atomic Ray, Delta Attack, or Blaster (hope it's not Atomic Ray, it murders you on the very first turn, and hope the others doesn't target your BM either)
2 - Surge Beam (cast Thundaga)
3 - Rainbow Wind, Emission, or Atomic Ray (Elixir)
4 - Surge Beam (Thundaga)
5 - Two Actions in a row:
Delta Attack, Blaster, or Surge Beam (Hope it's not Surge Beam and hope it doesn't target your BM)
Maelstrom, Quake, or Rainbow Wind (If Maelstrom, Elixir, Quake is Game Over without Float, Hope the last thing don't hit your BM)
6 - "Targetting" (Turns attacks against itself next turn) (THUNDAGA)
7 - Rainbow Wind, Emission, or Atomic Ray (Elixir)
8 - Surge Beam (THUNDAGA)
Also if I use my Dragoon, then the BM can care less about Thundaga-ing the Dragoon, I just have to pray that Omega doesn't fuck the BM up...
Counters all damaging attacks with two actions; likely Rocket Punch but can also do Mustard Bomb or Circle (Just hope they don't target the BM)
EDIT: Nope, not doing Omega anymore, it's rage inducing.
EDIT2: I defeated Shinryu instead.
The trick for this is not using Coral Ring at all. Equip Hermes Sandals on all, then equip the Chicken Knife to BM for speed. Enter the battle, change to Wonder Wand w/ Berserk, hit him, and then pray that he misses a lot, with helpings of Phoenix Downs.
EDIT3: Neo Exdeath down.
Now should I start a new run or finish Omega, I'm towards the former.