Kretin

Kretin is a molecule with two forms called Alpha Kretin and Beta Kretin who, in Mario & Luigi: Bowser's Inside Story, kidnaps Princess Peach. After a long chase in the Flab Zone, Mario & Luigi finally reached Kretin. Using the spin move, Mario & Luigi free Peach from the grips of it, but immediately gets attacked by Kretin.

In battle, Kretin will begin in its Alpha Kretin form. Each individual unit of Kretin can be either red or green, and can only be damaged by the Mario Brother of the corresponding color. When one unit receives enough damage, it turns blue and becomes invulnerable. After all the six parts of Kretin are blue, it will fall apart and become Beta Kretin. All but one of the units will be invulnerable in this form, so the vulnerable unit will try to hide by rapidly switching places with the others.