Shy Guy ghosts, by sucking their masks off with the Poltergust 3000. After that you can shine your light on them and capture them. After that the Whirlindas appear and Luigi must stand on one of the round spinning tiles and face away from them. After a while, Mr. Whirlinda will say the word "Dance". The Whirlindas will strike a pose, making them vulnerable. You can then suck them up, and get the key to the storage room.
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