AtmaWeapon

  AtmaWeapon  Hp : 24 000  Weaknesses : None

He can be pretty tough if your levels are low. I reccomend using either Terra, Sabin, Mog or Strago in your team along with Shadow. It's not a bad idea equipping everyone with Gaia Gear before this battle, as it will absorb his Quake spell. Terra should cast Bolt2, Sabin use AuraBolt, Mog use the Earth Blues Dance and Strago use the Aqua Rake Lore while Shadow throws Shurikens. AtmaWeapon can cast Flare, Fire2, Bio, WWind and Quartr. At a certain point in the fight, he will use MindBlast, a status attack.  Have relics to prevent Petrify and Zombie which are of no doubt the worst status ailments to get. Just stay healed and hit him hard, he should fall pretty quickly.