You don't need Zell to beat Omega, but you do need to be fast:

Squall: 100 K
Quistis: 200 K
Irvine: 70 K (fast) / 40 K- 60 K (pulse)
Eden: 60 K
255 mag triple meteor: um...3 x 10 x 9999 = 300 000 ish?
Just figure out how to add up to 1 mil.