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. He also consistently appears in sports games and spin-offs, and even featured as a playable character in several sports games.
Petey Piranha was thought to be a loyal follower of Bowser, but this was undetermined until Mario & Luigi: Paper Jam showed Bowser directly giving him an order. It has been suggested by bios for Mario Superstar Baseball and Mario Party: Star Rush that he is the ruler of his kind, as well as by his Japanese name, Boss Pakkun, as “Pakkun Flower” is the Japanese name for the Piranha Plant.
He has multiple special powers and abilities that set him apart from normal Piranha Plants, including spitting Goop, flying using his leaves, and attacking with vines. Several other “Giant Piranha Plant” characters appear throughout the Mario series, many of which bear a resemblance to Petey, including the Mom Piranha from Mario & Luigi: Superstar Saga, the Dino Piranha and Fiery Dino Piranha from Super Mario Galaxy, and the Peewee Piranha from Super Mario Galaxy 2. He also has a paper counterpart, who appears in Mario & Luigi: Paper Jam.
In Super Mario Sunshine, Petey Piranha is stationed in Bianco Hills, where he covers the landscape with Goop. While Mario is on the landscape in front of the windmill, where the Polluted Piranha is fought, Petey Piranha shoots Goop at Mario from a very far away distance.
When Mario faces him on top of the Big Windmill, Petey Piranha’s enormous weight makes the windmill’s roof collapse, causing Mario and him to fall into the windmill. Inside, Petey Piranha attacks Mario by spitting Goop at him, and also headbutting him if he comes too close. However, just as he is about to spray Goop, Mario shoots water into his mouth with F.L.U.D.D., causing his stomach to become filled with water and making him fall to the ground. Mario then Ground Pounds Petey Piranha’s belly three times, causing him to dissolve into Goop and give Mario a Shine Sprite.