Emerald uses an attack called Aire Tam Storm, which does 1111 damage for each materia a character has equipped. Therefore, you should not put more than eight materia on any one character. A good strategy would be to put only two materia on one character, making sure that he or she has 9999 HP (use HP Pluses if needed). When Aire Tam Storm hits, if he or she is at full health, the character will enter Lucky 7s mode, wherein they will attack Emerald 64 times, doing 7777 damage per hit. This will take off almost half of Emerald's HP. There will be a time limit on the fight if you do not have the Underwater Materia equipped, which you can get by using Morph on a Ghost Ship in the Underwater Reactor at Junon, and giving the book you get to the traveler in a house in Kalm. Possible strategies for the fight include constantly miming Knights of the Round or other summons, pairing Phoenix with Final Attack for safety, pairing Mime with Counter, pairing a strong summon with HP or MP Absorb, or just fighting and keeping your party alive as long as possible.
you fight it
Yes.
72 hours
go to the village that you got arc
You get it after you beat Hecatoncheir in the Cave of Shadows.
to beat him use chaos sharo, then when your GB is filled up,use it
You don't beat him. You offer him dried meat, and he'll help you.
weakness is holy
Have Kain jump on her when she turns into a tornado
you unlock a alternitive ending
...................... beat the game on all difficulty
cath groundon or maybe you can reach it with a salamence I did it on that way