Hello. I registered just to reply to this topic. I've been a fan of the Ghostbusters since, oh, 1985 or so. ^_-
I contributed the ending to “The New Ghostbusters” NES game (European Version) some time ago at The Video Game Museum. The address is http://www.vgmuseum.com/end/nes/a/newgho2.htm .
I also made the endings for both Ghostbusters and Ghostbusters II, but they aren't up yet, figures. Anyway. The ending in GB1 is just a screen full of text that says that you beat Gozer; in GB2, after you make it to Vigo with all four GBs, the game shows a display of all four GBs sliming him, and a newspaper headline appears, with the pictures of all four heroes, and how they saved New York. The credits then roll.
Oh, to beat Zool, just keep shooting. It took me five minutes to beat her, erm, it. ^^
Later!