I just did this BC second run yesterday.
my set up for both runs were
Rdm(me) Blm Brd Nin Nin Drk
first run we went 0/4
Was so close to winning Omega on all tries.
on the 3rd and 4th tries we got omega down to 10% and 5%.
We didn't plan for wipe, so when omega killed us we couldn't get back up.
We discussed our strategy and thought our blm nuked too much, causing omega to run around making it difficult for everyone to cure and move around.
So on our 2rd trip, we only had our blm regen everyone, cure and stun. nothing else.
Only seal+ancient when omega got below 5%.
It worked out really well.
VS Omega I haste all fighters and brd sing 2 mambo.
VS Ultima, we have no erase so we have brd sing march+mambo instead. I haste fighters whenever they have no slow on them.
We won in 35 minutes, 0 wipes. only 1 death by omega, which was our drk ^^
On a side note, every battle I used many stacks of of mulsum (8 stacks on the last trip alone) so that's almost a million gil spent by me alone. And I had to buy 5 CCBs total for all those runs. I'm the only high level crafter (fishing+cooking) in our static so I wouldn't mind supporting everyone with some gil :O as long as it helps passing the BC.