Instructions
Equip your characters with the following materia combination: HP Absorb plus Knights of the Round, W-Summon, Mime and Underwater Materia. Equip nothing else but those things.
Use a Hero Drink and summon Knights of the Round. Every time you do this, that character will gain 9,000 HP. These points will come from Emerald Weapon's HP.
Mime this attack continuously until Emerald Weapon is defeated.
Keep the materia you have equipped low. This is essential to remember because the more materia you have equipped, the more damage Emerald Weapon can do with his Air Tam Stomp. For example, if your party has 4 materia equipped, then his attack will do 4,444 damage. If you have 5 materia equipped, this attack will do 5,555 damage and so on.