Petey Piranha is an abnormally large mutant Piranha Plant with a ring of petals on his head.His first appearance is in Super Mario Sunshine, and since then has become a common, recurring boss in Mario titles, despite seemingly being destroyed after each encounter.Once defeated, Petey Piranha attempts to get up while glowing a bright white light; he soon vanishes, revealing the key.Petey is the only boss of this game (other than Mega Goomba) who can be defeated in one hit with an item other than a Mega Mushroom, although with Petey, this requires precise timing.
When he hits the ball with his club, a golden streak follows the ball, like the tail of a comet.In New Super Mario Bros., Petey Piranha is the boss of World 5, the ice world. When he is confronted by Mario or Luigi, he attacks by flying up high, then dropping from the sky, attempting to crush Mario or Luigi beneath him with a move similar to the Ground Pound.Many Piranha Plants appear in Petey's castle, a subtle hint that he is going to appear as the boss at the end. Since the floor is made of slippery ice, after attacking, he slips and falls. After two hits, he starts his attack by jumping from side to side.In this game, he is an unlockable character, obtainable by completing all side games (excluding the Birdie Challenge) on beginner, intermediate, and expert.His large size makes him the most powerful golfer in the game, capable of hitting the longest distance and launching the ball with a higher trajectory than any other character.