As one would expect from their name, they look like the ghosts of immigrants from other countries. They pulled a lot of pranks on Janine, such as hanging her furniture upside down and then dropping it, having her bed float so that she falls and hurts herself getting out of bed, and making frogs come out of her shower.
When she had enough, she donned a uniform and went to her apartment with a Proton Pack and a Trap. She ends up being outwitted by the ghosts, but Slimer was with her and captured the ghosts by opening the trap and holding on tight so he didn't go in there as well. When she went home to tell the Ghostbusters, she saw that they had disappeared. To find out what happened, she put Slimer into the Containment Unit to spy on the ghosts. When Slimer gets the information he needs, he ends up being chased by two of the Street Thugs ghosts. The Frankenstein Monster and the Immigrant Family ghosts join the two ghosts in their chase. They get real close to getting out of the Containment Unit and catching Slimer, but go back in when Janine points a thrower at the ghosts and tells them not to even try to escape.