ULTIMA WEAPON

You'll first fight this boss in Mideel after going back to see Cloud and Tifa. He's pretty easy, so you just want to pummel it with your strongest summons and magic until it flies away. Make sure you have plenty of        X-potions. Once you get to the thrid disc, he'll be flying around outside. He'll land in many different places, being Mideel, Nibelhiem, Rocket Town, Wutai, and Cosmo Canyon. After finding him, you must fight him, and after injuring him enough, he will fly away once again. He only has 100000 HP, and he can't heal himself after battles. Once he's low, at like, 10000 HP or so, he will be hovering above Cosmo Canyon, his final resting place. Use the same techniques there and defeat him. Make sure that the character with the Enemy Skill Materia gets the last blow, because he does a final attack called Shadow Flare, which will kill you if your HP isn't high enough. He crashes and makes a hole, and you can now access the Forest of the Ancients if not already.