Battle
Fighting Kuja is not for the feint of heart. So I'm here to help you through the two times you have to fight him.
Level: 64
HP: 42,382
MP: 9,999
Steal: Light Robe, Carabini Mail, Ether
Location: Pandemonium
Recommended Party: Zidane, Steiner, Amarant, Eiko
This battle isn't too tough, all things considered. If you got through the previous ones just fine, you should be able to handle this. Kuja only uses attacks that hit one person, which is nice. A favorite of his is Thundaga, which usually does anywhere between 1000 and 3000 damage, but you can easily counteract that by equipping your party members with coral rings (which will absorb the thunder). He also uses Demi, but you can't do much to defend against that. I think it reduces your health by half of what you currently have. It sucks when you're at full health. Use your usual attacks with Zidane; cast Regen with Eiko and heal; attack with Amarant; and maybe use some of Steiner's special techniques. If you want, you could substitute Amarant with Freya. Just make sure you keep everyone alive, and you'll be alright. At the end, he's supposed to hit you with an Ultima, so don't think you did anything wrong!
Though you're Kuja-free for awhile, you'll encounter him again toward the end of the game...
Level: 76
HP: 55,535
MP: 9,999
Steal: White Robe, Rebirth Ring, Ether
Location: Crystal World
Recommended Party: Zidane, Steiner, Vivi, Eiko
Here's the heavy hitter: Kuja uses Flare, Holy, Flarestar, Reflect, and Curaga. Tough, huh? But now that you know what he uses, let's find a way to work around that. First of all, if you're in the level 40's (like you should be!) you'll be fine. I recommend casting Regen on everyone (if you don't have auto-Regen equipped), and Eiko's Holy attack is invaluable. Vivi and Steiner are awesome with Flare Sword, and Zidane is particularly useful if he's about to trance. Just be warned: once half of his health is gone, he starts to counterattack, most likely with Flarestar. His spells are heavy hitters, but it's not so bad if you keep everyone alive. Just be sure to have a healthy stock of ether and to give it to people before they're out of it. Otherwise, you're screwed. At the end, you get to see Ultima one last time. It's kinda pretty, isn't it?
And after that, say good bye to Kuja... it's a bittersweet moment :(