(Thanks to Scott B)
After this he decided to become good and pulled out some golf clubs and started Golfing with the brothers and company in Mario Golf: Toadstool Tour. So that's the story of Petey Piranha Plant.
Petey Piranha was first seen in Super Mario Sunshine. He was the first Boss. At first, he actively sprayed goop from the top of a windmill in Bianco Hills. Mario soon stopped him. Unusually, Petey Piranha was able to actively attack Mario, but never did any real damage. Later on, Petey struck back by covering Bianco Hills in goop – again! Somehow, Petey was so bored he fell asleep. When Mario woke him up, he began flying. He flew around throwing up paint. After being defeated, Petey ran off to practice some Sports skills.
In Mario Golf for the Gamecube, Petey arrived late and so joined the team of golfers as a Hidden Character. He proved to be the strongest known golfer in the entire kingdom.
Next up came the biggest challenge of them all; Mario Kart: Double Dash!! Teaming up with King Boo, he was able to use any character's Special Item. His standard kart was the Piranha Pipes. Some players refused to play against Petey, as the "using all Specials" Special ruined the point of specials altogether. Petey was reportedly disqualified and not allowed to enter the Nitro or Retro Grand Prix.
Petey now started using his Goop powers in Sport. In Mario Power Tennis, Petey was once again unlockable. At this point, he was already viewed as one of the regulars of the Mario universe. His Power Shots revolved primarily around the use of paint.
More recently, Petey appeared as another unlockable Power character, this time in Mario Superstar Baseball. He appears to have developed a love for competitive sport. Interestingly, information from the game states that Petey was created by a mutation caused by "The Piranha Boss" – whether referring to Petey (as a Boss character) or to another, higher-level of Piranha, is as of yet unknown. It also shows that Petey's leaves evolved into primitive wings.
In Mario & Luigi: Partners in Time, Petey appeared as the boss of Gritzy Caves. This time, Goop was nowhere to be seen. Suggesting that he was around long before Mario Sunshine (in terms of Chronological order, not game order), although there may have been two different Peteys over the years. Petey ate Princess Peach and Kylie Koopa but the Mario Bros. saved them.
Finally, he also appeared in the game: Super Princess Peach. This time, he was the first Boss Peach had to take on. Again, without Goop powers, but retaining his ability to Fly. Petey Piranha seems to have developed almost as many skills as Mario himself. This time he was referred to as "Boss Piranha Plant".
(Falling through the windmill) "Urrh ooh!" - Super Mario Sunshine
(Shooting sludge) "Reaahh roooooooo!" - Super Mario Sunshine
Attack Pattern:In the first battle he stays in one place and shoots sludge. In the second one, he flies between sludge shots. He can also throw tornados. Oddly, none of his moves are capable of doing damage.
Basic Strategies: When he opens his mouth to shoot sludge, shoot water in his mouth until he falls over. Then ground pound his stomach.
Advanced Strategies: None right now.
Mario meets Petey Piranha from Super Mario Sunshine (mp3, 149 KB)
Petey attacks from Super Mario Sunshine (wav, 94 KB)
Petey attacks from Mario Kart Double Dash!! (wav, 56 KB)
Petey bats from Mario Baseball (wav, 928 KB)