From the Super Mario Wiki
Temper Terrors are a normal elemental sub-species of the Gold Ghost in the game Luigi's Mansion. These light blue ghosts have fireballs protecting their hearts. Temper Terrors appear in the 2nd floor Washroom and the Sitting Room, although a few Temper Terrors appear in the Bathroom during the blackout. In order to expose their heart, Luigi had to shoot water from his Poltergust 3000 (after vacuuming a Water Elemental Ghost) at the Temper Terror, dousing the fire surrounding the heart. The Temper Terror has a punch attack, identical to the one used by the regular Gold Ghost, which must be dodged.