Oozers are orange and slim ghosts with white eyes and mouth. They are more aggressive then Hiders which they move faster and attack more frequently, Oozers don't have protection like Goobs.
Oozers are first seen in the Entertainment Room of the Mezzanine after defeating Chef Soulfflé. They will throw balls at Luigi, Oozers will hide very fast and be fought throughout the game. They attack by throwing objects and sometimes even in a set of three instead of one.