Sin (fin)

Sin is a boss in Final Fantasy X that attacks the party while they are traveling on the S.S. Liki. During the battle, Sin will not actually fight itself. Rather it shoots out Sinscales to do the fighting while it remains out of range of physical attacks. When the three Sinscales are defeated, three more are brought out to take their place. Players may want to only kill two so they only have to deal with attacks from one. Lulu's Magic, Kimahri's Lancet, Wakka's regular attacks, and Yuna's Valefor Summon can all hit Sin.

If the player has the patience, they can easily level up several times here. Use a party of Tidus, Wakka, and Kimahri, and have Tidus use Cheer five times to boost their Strength. The three should now be strong enough to kill the Sinscales in one hit, and when they die, Sin shoots out three more. With the ability to kill the scales in one attack, the player can kill them in one round without getting hit, or at least not seriously damaged, since Cheer also raises Defense. The Sinscales each give 2 AP, or 3 AP with Overkill, and as there is an infinite supply, the player can spend as much time as they wish killing them to earn AP.