From the Super Mario Wiki
The Glad Piranha Plant is an enemy found on Vibe Island in the game, Super Princess Peach.
Unlike regular Piranha Plants, Glad Piranha Plants are yellow, and are capable of hopping up, like Petey Piranha. They also come with the ability to spit fireballs, making them very formidable.
According to the game's Glossary, it "Dances around happily and spits fireballs."