From the Super Mario Wiki
“The bird, it warbles, TWEET!
Piccolo is an optional Pixl in the game Super Paper Mario. It takes some time to run a series of errands to earn Piccolo. Piccolo plays music when the player presses on the Wii Remote, and is named after the instrument Piccolo, a small flute. She can play music that can cure Mario and the team from any curses placed upon them by Cursyas and she can put the Underchomp to sleep. In addition, Piccolo can make blocks with her emblem disappear, usually revealing treasure chests, such as the blocks in the third floor Flipside and Flopside outskirts, which contain a Merlee and Nolrem Catch Card, respectively.
When Piccolo is equipped, different tunes will play depending on which character is out, and the tune she plays to heal them is different too. Mario and Luigi's healing songs are Italian, Peach has a cheery lullaby-like song, and Bowser has a metal song. Piccolo's music is also affected by the place the player plays the song in. Finally, Piccolo causes the player's jumping and Bowser's Fire Breath to make the original Super Mario Bros. sound effects.
Here are the errands to run to earn Piccolo:
Card Type: Rare
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