They are not impossible to beat!!! Eventually it's quite easy really

(You have to be level 99 for this) The best way is to have two of the girls wear the Dark Knight garments (Or Mascot if you have this) and it must be FULLY MASTERED. Equip them with an accessories that have HP + 100% and Defense + 100% (If you have this that is, if not use anything that comes close to this).
And one girl must wear a Gunner garment (wich has to be on the Highroad Winds grid so you can act first) and has to be equipped with Cat Nip, she also has to be in yellow health (low) because now if you use the "Happy Trigger lvl.3" command it will do 9999 every hit!!! (swift hand needed) <img src="/images/graemlins/tongue.gif" alt="" /> and equip her with Auto-Haste!!! (Speed Bracer)
Now if you encounter a big ol' baddy you just have the Gunner do Happy Trigger lvl. 3, if they're not dead yet now it will attack and attack hard. Hopefully the Dark Knights will survive, revive your Gunner with a Phoenix Down (!this will keep her in yellow!) and repeat the same!
Pfew... <img src="/images/graemlins/blush.gif" alt="" /> (and if you DO have Mascots, Trema is a goner! :devil: )