Biran and Yenke
HP - Varies
AP - Biran: 4,500; Yenke: 4,500
Weakness - None
Steal - Lv. 3 Key Sphere (Biran)
Too easy but useful. Use Lancet on Biran and Yenke when they use that attack in order for you to use it. Just attack and heal and you'll win. Defeat Biran first.
Then head up the mountain until you reach the save sphere. Go up that hill to meet your special friend... Sumo!!!!
Seymour Flux and Mortiorchis
HP - Seymour: 70,000; Mortiorchis: 4,000
AP - Seymour: 10,000
Weakness - None
Steal - Elixer
This battle is much tougher than the last battle with Seymour. Cast Hastega and protect on everyone. Seymour will use Lance Of Atrophy to inflict you with Zombie, then he'll use Full-Life or Curaga to hurt you, but just use a holy water before he attacks again. Make sure you don't let Mortiorchis use the Total Annihilation attack, you will most likely die from it. Use all of your aeons overdrives and pay Yojimbo 3/4 of your money and pray that he'll use Zanmato or Wakizashi. If Seymour still has HP left after this, use your party members overdrives to finish Mortiorchis and Seymour off.
Now you'll be in the caverns. During the first trial, hit the middle with Wakka's blitzball. Use logic. Second trial is underwater, guide each person through there color. Green - Rikku; Blue - Tidus; Orange(looks like red to me)- Wakka. I also found this part very funny. Then you'll be able to move outside and. . .
Sanctuary Keeper
HP - 40,000
AP - 11,000
Weakness - None
Steal - Turbo Ether
This battle is so easy. I got it done in about 6 mins. I just use Yojomo about 4 times and just pay 1 gil.