The emulator filtering on that video is out of control! I think this one is probably a more accurate representation of the visuals:https://www.youtube.com/watch?v=yq8KPw8Mx98
And yeah, unlicensed developers -- mainly from Taiwan, China, and Russia, I think? -- pumped out a ton of bootleg fighting games for different systems, many of which I assume used the same engine. The NES, MSX, Master System, and Genesis all have a bunch.
Heck, the Master System even has legit ports of the Mortal Kombat games, which makes sense since they were released on the Game Gear. So if the Game Gear and Game Boy can swing MK, no reason the NES can't manage a version of it.
But most of these downports -- even the legit ones! -- have atrocious controls and slideshow visuals.