Netflix UK has season 1 78 episodes , season 2 13 episodes , season 3 has 8 , season 4 9 and season 5 8
I assume wrong order or something as my favourite episode "The Revenge of Murray the Mantis" is in season 1 but it's no on the dvd of season 1 and most list as season 2 but that's ok. What's bugging Nevis it's like 117 episodes I thought there was more unless the rest are Slimer and the real ghostbusters which was less enjoyable but I'd still want it.
There are some episode listings, which have mostly fallen out of favor, that consider the 65 syndicated episodes as part of Season 1. They do fit together with them in some ways, what with JMS script editing and Lorenzo Music and Laura Summer in the voice cast. So at first glance that looks right up until the end of "Season 3" (aka Season 4, the ABC 1988 season)
So in summation:
Season 1: ABC 1986. 13 Epsodes.
Season 2: 65 Syndicated episodes. Sometimes considered part of Season 1
Season 3: ABC 1987. 13 episodes. Sometimes considered Season 2
Season 4: ABC 1988. 8 episodes. Sometimes considered Season 3
Season 5: ABC 1989 (post GB2). 8 half hour episodes, 12 fifteen minute episodes. Sometimes considered Season 4
Season 6: ABC 1990. Sixteen episodes. Sometimes considered Season 5
Season 7: ABC 1991. Four episodes. Sometimes considered Season 6
Maybe the Spook Central episode guide can be of help in determining which ones are missing:
Slimer! is another ball of wax, a number of fifteen minute episodes that ran in 1988 (before an after the RGB episodes) and rerun sometimes in 1989. Again, look at the Spook Central guide: