Use two or three Phoenix Downs on it to kill it instantly.

When fighting in the Monster Arena, even if you die, you still keep any items you may have
stolen.

Auron: Find different Jeckt Spheres laying about the world. Some of these will give Auron
a new Overdrive. You need to find all ten to get Auron's final Overdrive. 

  Kimari: Use the Dragon Sword ability to drain HP and MP from the enemy. If the enemy has
a Blue magic skill that Kimari can learn, he will gain it automatically. The only one that
is difficult to get is "Sunshine", which you obtain from the Omega Weapon. 

  Lulu: Rotate the Right Analog-stick clockwise as fast as possible. The number will go up
the more you rotate it. The more you level Lulu up, the easier it is to cast multiple
spells. 

  Rikku: Rikku's Overdrive combines items to create special attacks and power-ups during
battle. You have to choose any two items to combine. Note: Two of the same kind will work.


  Tidus: Just keep using them over and over. After a while, he will learn his next
Overdrive. 

  Wakka: You can win new Overdrive roulette (slots) types in the Blitzball Ranking and
Tournament modes.