Sinspawn Ammes- (HP 2400, 1000Overkill, Weakness None)
Your first real boss battle, Tidus and Aaron start with almost full overdrives, use Aaron's to kill the sinspawns. Ammes will only attack with Demi, this attack will only take away 1/4 of your current HP so you dont even need to use any potions even with your HP at only 1. Keep hitting it and you will kill it. Use the save-sphere after the fight to regain all your HP.
Geosgaeno 1st Battle- (HP 90, Weakness None)
You can get away ether by trying to escape each turn or attack the beast 3 times, if you attack it will counter-attack, so keep your potions ready.
Klikk- (HP 1500, 400Overkill, Weakness None)
Have Tidus attack over an over, when his HP gets low have ???? use a potion on him, ???? attack's are weak so use grenades if possible.
Tros- (HP 2200, 600Overkill, Weakness None)
After a few hits, Tros will move to the other side of the chamber, you can then choose the command "Stand By" this will raise some of your HP. The next time he does this you can do the command "Pincer Attack" and both people will surround him. Have Tidus slash him over and over and have ???? steal grenades and use them.
Kimahri- (HP 750, 300Overkill, Weakness None)
At the start of this easy to win battle, cast cheer on yourself a few times, this will strenghten your defence and raise your attack. Just keep hitting him only use a potion when you are in the yellow zone. This is a quick battle, if you cant kill Kimahri then I would recommend not even trying to beat the game.
Sin's Fin[SS LIKI]- (HP 2000, 1000Overkill, Weakness None)
Sinscales[SS LIKI]- (HP 200, 400Overkill, Weakness None)
There is a stratagy here, kill two of the sinspawn and dont touch the other one. Get Wakka, Lulu, and Tidus. Keep Tidus casting cheer. Wakka needs to use his balls to hit Sin. Lulu can use any black magic spell. Just keep doing this and you will be cool.
Sinspawn Echuilles- (HP 2000, Weakness DARKNESS)
Only Tidus and Wakka can battle this bad boy. Have Wakka use Dark Attack, this will stop him from draining your HP. Forget about the little sinscales, they will just keep comming back. After Sinspawn has three turns, re-use dark attack. Soon he will use BLENDER. Just keep using a potion when in the yellow zone. Wakka and Tidus can take him out.
Lord Ochu- (HP 4649, Overkill 800, Weakness FIRE)
THIS BOSS IS OPTIONAL You can run around him if you want!
Keep Lulu in your party and have her use fire over nad over. If your Tidus has haste, then cast it up, especially on Lulu. Have Wakka use scilence attack to stop the magic flow. Kimahri can just keep hitting him. Use Yuna's Esuna when someone gets poisened. When you need a break summon Valfore and use his fire magic. Just keep this up and you will win.