- Normal: "A humongous green menace formed by the rogue cactuars that fled to Cactuar Hollow and refused to grow up. Giant and green, but definitely not jolly."
Oversoul: "One big, angry cactuar. It attacks with magic that gets more and more powerful as the fiend's situation gets worse and worse."
To enter the Aeon Cup in the Coliseum, the player must capture and raise the story levels of eight special creatures. These creatures will immediately be available to be released upon capture, however, what the player has to do is raise their story levels by three and then release them. This will change that particular creature into an Aeon. The Jumbo Cactuar is one of these eight creatures.
If it is not Oversouled, then have some Dark Knights use Darkness to wipe out the little Cactuars. Jumbo himself will not attack, so just hit him until he dies.
If he DOES Oversoul, use Shell, Reflect, Mega-Potion, have Dark Knights spam Darkness or Black Sky. You could also have Lady Luck use Flare and/or Ultima with Magic Reels. It is also recommended to have elemental-absorption abilities in the case that it does manage to hit with one of its elemental spells so that the party will take no damage throughout the fight. Not a very difficult enemy at all to defeat.