Seeing as you claim to be my neptune I figure I can throw in my 2 cents and try to help out.

1: Barbariccia is a wind elemental not an earth (keep that in mind)
Remove Tellah and replace him with Kain
Have shell and protect on everyone
Have Yang focus 2-3 rounds then let him attack
When she takes to the air have Kain bust her back down again with Jump
Other then that have pleanty of cure items and white magic availible.
Probably will take a while to defeat her but this tactic worked for me if I remember correctly.