Welcome to the Slimer! And the Real Ghostbusters guide at TV Tome.
The season had it's name changed during the 3rd season to The Real Ghostbusters. 
This wasn't so much a spinoff, as a continuation of the Real Ghostbusters cartoon.  It was an attempt to retarget the show at a younger audience, by having shorter Ghostbusters episodes, followed by short "Slimer" episodes where Slimer had to deal with some problem as well as a few secondary characters that didn't appear on the regular show. In general, this show was considered to be the beginning of the end for the series.  It failed to boost the show's popularity as it both alienated older fans and failed to attract younger ones, and it's also generally agreed that quality of animation suffered considerably when this season started. If you like this show check out The Real Ghostbusters.