From the Super Mario Wiki
The Cannon Pianta is a blue Pianta in Super Mario Sunshine. He first appears in Delfino Plaza inside the red Cannon near Ricco Harbor. He tells Mario that the Cannon isn't ready and may take a while to fix. It will not be ready for use by the player until after the scene where Shadow Mario kidnaps Princess Peach and flees to Pinna Park. The Cannon Pianta later appears in Pinna Park, but only on the beach. In the second episode, a Monty Mole takes his place, though he returns in the third episode after Mario has defeated the Monty Mole.