The Way To Win
Here is what to do. Compared to the last few bosses, this aerial encounter with sin should not be too difficult. When Fighting the arms, have Tidus or Rikku use their trigger command to talk to Cid if Sin is powering up for a gravity attack. Cid will move the airship out of range, so the painful spell will miss entirely. Auron's armor break and mental break skills will facilitate the Sin-killing process greatly. Just keep tossing your best spells and strongest attacks at the fins and you will win. Aeon Overdrives will make this battle even easier, but you do not really need them. After the fins fall, your party faces two more bits of Sin. The strategy remains the same: Whip out the armor break, cast some nasty spells, and slice it with your blades.
-Hope This Helps!! 😎
