Absolutely loved Double Dash and the addition of two riders on a kart. Also has the best course of all-time... Baby Park!!!! I could play that course with friends for hours and hours!!!
I've found that Water Ski actually plays very well with the ProLine joystick. Other than that, Ms. Pac Man, Pole Position 2 and Robotron: 2084 are all alright. Games that require you to press buttons frequently are very, very bad though. lol
Alien Storm for the Sega Genesis. Didn't really have too many choices though. The only other Halloween-themed coop game I have is Zombies Ate My Neighbors... but I like Alien Storm better.
This isn't related to this topic but I just had to say something because I'm so happy to see Harold the dog from the Mr. Rossi cartoon as your avatar. You just made my day! I used to watch those cartoon movies as a child and I've never met another person who knew who Mr. Rossi was.
Killer Instinct - SNES - Got completely destroyed by Eyedol... had to give up after about 10 tries to beat him... Wipeout XL - Sony Playstation
Joe and Mac - SNES
I was impressed back in the day, although the controls (unless you had the arcade stuff) were pretty tiny. All the half circle, full circle, quarter circle moves and having to keep doing them over and over to keep up combos. Had fun with it, though.