Sin Kill

1
Prepare your party before you fight against Sin. Include Auron, Tidus and Wakka in your group.

2
Move Cid so that he is placed to the left side of Sin's fins.

3
Attack Sin's left fin with Auron's spell "Armor Break" and "Mental Break."

4
Replace Auron with the Lulu character and use Lulu's magic spells such as "Watra," and "Fira."

5
Cast the spell "Hastega" by using the Tidus character to perform the spell.

6
Move towards Sin's right fin and do the same process. Have Auron use "Mental break" and "Armor break" and then switch Auron and Lulu. Have Lulu attack with her spells.

7
Attack the next part of the battle, which is against "Sinspawn Genais." This creature has a large shell that it hides in. Use the Auron character to cast spells until "Sinspawn Genias" goes into its shell and then replace Auron with Lulu.

8
Cast spells with the Lulu character; include the spells "Fira" and "Watra." Focus on killing the Sinspawn Genias so that you can move on to the main battle against Sin.

9
Regroup your characters before the battle with Sin. Include Lulu, Wakka and Tidus in the party.

10
Cast the spell "Hastega" by using the Tidus character to perform the spell; then switch over the Tidus character to Rikku.

11
Attack Sin with basic attacks from the Wakka character. Attack Sin with Lulu's magic spells and have Rikku cast the spell "Use."

12
Swap the characters so that you have Auron and Tidus back in the party, and Lulu and Rikku are not in the main party. Use Auron's "Mental Break" and "Armour Break," and Tidus' spell "Hastega," until you defeat Sin.

Tips & Warnings
Heal your party frequently with potions and healing spells so that all the characters make it to the final battle.

You have 12 turns in which to defeat Sin. If your party does not defeat Sin in 12 turns, he will automatically win.