HeDanny: I.. Don't think Mortal Kombat, Street Fighter, etc are side scrollers? Things like Karateka, R-Type etc are "side Scrollers". Things like Final Fight, Golden axe are also side scrollers, but they have that horrid "2.5D" thing that made them all terrible to play. Games like Mortal Kombat, Street Fighter I believe are usually considered Tournament Fighters, or just "fighting games".

i don't like Tournament Fighters. The last one I played that I actually enjoyed for the game in the game was International Karate plus. Me and my mates would play that one for days on end Just to see how far we could get. If there really was an end to it, we must have sucked too hard to ever reach it.

http://www.youtube.com/watch?v=wDko0WVJUr0
in the 3d era, I also have all the Dead or Alive games except the most recent. I don't have those because I like tournament Fighters. I have them for other reasons. Also, the Beach Volleyball games are far and away my favorite of the bunch.

http://www.youtube.com/watch?v=oUY7PzkRkGs
Oh I just remembered there is one from the simple series called "the Cat Fight" which is bloody hilarious! I went through a stage for a few months where if it was from the simple series I pretty much just bought it due to imo them almost always turning out to be the gaming equivalent of"Plan 9 from outer space" is for movies. I just love crap, and those simple series games were some of the crappiest, but in the most wonderfully entertaining way.

http://www.youtube.com/watch?v=afLJf7z0RVc
There was another one I bought once because it has Link from the Zelda games in it. I can't remember what it was called and I think I only played it in total for less than an hour, which was long enough to play Links "story" a few times. Only bought it because it was in a dump bin for a few bucks, and I like Link.