Koopeleon

Koopeleons are Koopas that live in the Toadwood Forest in Mario & Luigi: Partners in Time. They resemble a Koopa and chameleon hybrid with a blue shell, green skin, large eyes, and a long, curled tail. Koopeleons have the ability to turn invisible. To attack, a Koopeleon runs into its foe, delivering damage. This attack can be dodged and countered with a jump attack. If damaged, a Koopeleon becomes visible. Koopeleons take critical damage from fire attacks.

Koopelons have their own variant, which are called Gold Koopeleons.