Super Mario Sunshine, GameCube, 2002 Super Mario 3D All-Stars (via SMS), Switch, 2020
Eely Mouth is a character who, so far, has appeared only in Super Mario Sunshine, where he is a boss that Mario must fight to earn a Shine Sprite.
Unlike most other bosses, Mario's job isn't to kill Eely-Mouth. Instead, he must clean Eely-Mouth's teeth, which are somehow causing pollution that's poisoning the water of Noki Bay. His official art shows him as blue, but he appears more purplish in-game.