Confusing
I kind of like your idea of a Mario Kombat concept, but this had poor execution. The sprite animation could improve, and the screen should have been smaller. Also, there should have been a background, and some sound effects should do. I hated that you used the same sprite over and over again, and how it was pretty dull.
The ending was highly disappointing, the zoom-up was completely unnecessary and it was confusing to how Luigi won the fight.
There could have been a plot to how they were fighting, and there could have been more action. You could have added in more characters and make it fit the Mortal Kombat theme.