From the Super Mario Wiki, the Mario encyclopedia
The Purple Punchers (a.k.a. Pink Punchers, Purple Ghosts, or Pink Ghosts) are the second species of normal ghosts Luigi encounters in Luigi's Mansion. As the name implies, these ghosts try to damage Luigi by giving a left or right hook to the plumber; ten HP is lost for each successful uppercut punch. Luigi can stun Purple Punchers with his flashlight, and then suck them in with his Poltergust 3000. After, he can spray them with an element to get rid of them. In an earlier version of the game, Purple Punchers had 30 HP each. However, this was changed to 20 in the final version for unknown reasons. This pre-release screenshot can be seen on page 19 of the US Luigi's Mansion Instruction Book.
Luigi's Mansion (Nintendo 3DS)
Names in other languages