Normal: "A fiend that grows in damp places and releases a spore cloud when struck. It's slow but not to be taken lightly." Oversoul: "A fiend that grows in damp places and attacks with magic and spore clouds. When its HP gets low, it enters a sort of "Magic Berserk." It's not pretty." — Scan
The Mycotoxin is an enemy from Final Fantasy X-2. They are slightly difficult enemies to defeat, but not as tough as earlier Fungus enemies. Hit it with high-powered Fire-elemental attacks such as Flametongue, Fire Breath, or Fira, and it should fall easily. In Oversoul, having Reflect or Shell helps immensely.
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 Mycotoxin is one of these eight creatures; capable of being changed into Valefor.