Iron Cleft

Iron Clefts are a powerful sub-species of Clefts found in Paper Mario: The Thousand-Year Door.

Iron Clefts are larger than normal Clefts and have a blue coloration. As their name implies, they are made of impenetrable metal. Even if Mario manages to have the Piercing Blow badge equipped, they still won't take damage, and a correctly-timed Superguard will not deal them any damage either.

The only known Iron Clefts are the Armored Harriers.

Varieties of Clefts

 * Cleft
 * Bald Cleft
 * Hyper Cleft
 * Hyper Bald Cleft
 * Moon Cleft

Trivia

 * Yoshi Kid's Gulp provides the only known way to defeat the Armored Harriers. It is effective even when one Iron Cleft remains. If Grubba (or Jolene) asked the player not to use any FP, or not to let the partner attack, that would make victory impossible for that particular match. It is unknown whether or not they can actually make these demands for this particular fight, but it's unlikely.
 * Since every character in the major league would have to beat the Armored Harriers in order to stay ranked above them, it is plausible that they have other weaknesses (or that the Major League fighters knew their main weakness).
 * It is also possible that the Spike Tops in the Glitz Pit kept them in their place. The Iron Clefts have an Attack of 4, while the Spike Tops have a Defense of 4.