List of Boos in Luigi's Mansion 2

Boos are undead ghost enemies that reappear in Luigi's Mansion 2. As Luigi travels through the five mansions, there are Boos lurking around in each mission. There are 33 Boos in total (including King Boo). 22 appear normally, hidden within the missions. The remaining 10 Boos are the Boos that make up Big Boo in mission E-4. During the entire game, only 12 Boos are required (2 if Big Boo is not counted), however capturing every Boo in each mansion will unlock the bonus missions in each mansion. Each Boo requires the use of the Dark-Light Device to find missing objects. By collecting all of the Spirit Balls from the object, the Boo will appear. To defeat a Boo, uncover it with the Dark-Light Device, and pull on its tongue with the Poltergust 5000. Once the power gauge is charged up, release the Boo and it will bounce all over the room. Each time it runs into a wall, floor, or ceiling, it will lose 1 HP. After depleting its health to 0, the Boo will be able to be captured.

The following chart shows the mission the Boo appears in, each Boo's name, how much HP it has, what room it's found in, and how to reveal it.