The Cave Iguion is found in Yuna’s section of Via Purifico. It is an agile fiend, so physical attacks might not hit all the time, especially without Tidus or Wakka in the party. You could try using magic against it, since it is weak to Ice, but it does have high magic defense. However, its HP is fairly low, so Blizzara/Blizzaga should be more than enough to take it out. The only thing it does is a physical attack and unlike previous enemies of this type, there are no ailments attached to it.