you can only beat omega weapon if your HP is 9999 for all characters, or you are lucky. omega has a nasty move that does 9998 (not a move that reduces your hp to 1, but does 9998 damage) to all charactes. I was arrogant and assumed my HP would be reduced to 1 the first time I attempted Omega. I beat him on my 2nd time after refining my Gilgamesh Card.

Point is, you CAN find the Ragnarok and play the CC memebers (if you have to for Gilgamesh), or if you can find the Queen of Cards, she plays EVERY rare card that you dont have (minus CC ones, possibly).

Or you could defend.