The H2 Ghost was based on toy from The Real Ghostbusters toyline.
When the Halloween Deal was broken, one night in the 1980s, the H2 Ghost was sighted with both halves running from the Ghostbusters. The top half of the ghost attended the wedding of Dixie and Egon Spengler.
It consisted of two blue ghosts as a toy, but in the episode was recolored purple (Top Half) and pink (Bottom Half).
It wasn't shown fighting the Ghostbusters in the episode, but since it is based on the toy, it probably could squirt water and stack on top of one another to look like they were a single ghost.
- On page five of Ghostbusters Issue #6, several H2 Ghost dolls can be see in the Fantastic Land stand.