Finding Shine Sprites
Go out to the island where the man is stranded. You will see a gold bird flying around. Shoot it with your water cannon and a Shine Sprite will appear.
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Go to one of the rooftops in Delfino Plaza with a weathervane. You will see a man standing there. Talk to him and he will ask if you want to be thrown for one Coin. Answer "Yes". When he throws you, Mario will land in a room with a Shine Sprite.
Play and win the crate game in Delfino Plaza twice to get two Shine Sprites.