The best way to go is the Gates of Limberry Castle:

1) Have females equip Ribbons and have males equip Judo Outfits. This protects against the sudden death attacks the Assassins (Celia and Lede) use.

2) During the battle pummel Celia and Lede with spells that immobilize them. I recommend Don't Move with Math Skills.

3) Kill as many Apandas as possible while you do that. Orlandu and Agrias' Lightning Stab is invaluable. Apandas have Bio spells that can cause status ailments but your female units are completely protected with Ribbons.

4) Move Ramza just barely into spellcasting range of one of the Assassins. She'll use Ultima since she has no other choice.