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Polterguys are similar to the Phantom Guys of previous entries and transform into harmless blocks matching pressed Color Switches, although they appear upright and have active wind-up keys on their backs like their walking counterparts. They also have a spherical aura of fire similar to Pyro Guys rather than transparent bodies. In addition, they remain in the same spot rather than move in a given pattern, even though they turn to face Mini Marios. They are first encountered in Room 3-5.
Its name is based on poltergeist, referring to its somewhat spectral appearance.