The Trendmasters Extreme Ghostbusters Toy Line had one series of ghost figures, so children who had the Ghostbusters figures would have ghosts to battle.
The Slimer figure was much larger than portrayed on the show and came with a base and two food missiles(a donut and a hamburger).
The Mouth Critter was a squidlike ghost. While it never appeared on the show, it may have been inspired by the Dry Spell Spirit, as both are aquatic entities. It came with a missile to be shot out of its mouth.
This figure was loosely based on Le Maison. It came with canisters of slime to pour into the figure so it would drool slime. It was also able to fire its head off.
A figure of Samhain. Samhain never made an actual appearance on the show except for the intro. Oddly enough, the figure does not resemble Samhain's appearance in the show's intro. Samhain has a large orange pumpkin head like the way he appeared on The Real Ghostbusters, but the head can come off to reveal an eyeball. He also has a green whip and his black cloak can come off to reveal an emaciated skeletal body. It is interesting to note that he is the only villain from The Real Ghostbusters to have a figure in the toy line, which is odd considering the only ghost from The Real Ghostbusters besides Slimer to appear in an actual episode was the Grundel.