How do you beat illua easily in final fantasy tactics a2?

Answer 1

You should wait and do many other non-story quests to level up and master more abilities. You can get an advantage against Illua after finishing the 'I've been had, kupo!' quest.

You should be able to defeat Illua once all of your main characters are about level 45. I would recommend using a Parivir/Master Monk or learning Doublecast/Dual Wield to kill her as fast as possible (make sure you have a way to heal them though)

Try to focus on attacking Illua only, and ignore the others unless they are pretty powerful (The Illusionists and Lamia are quite powerful).