It's not. Funny enough though, this sprite was edited to look like Smoke, though I think only the color was changed - there were also a red Sentinel as Sektor, and a yellow Ironman as Cyrax.
edit: For those into sprites, the site is
http://canaanite.topcities.com : very nice sprite edits, game art and drawings. Too bad he doesn't have time enough to put entire sprite sheets together. Check out Miscellaneous for "Mushroom Kombat" animations which I helped make :selfpromotion