It isn't hard to figure out why this version of Mario is referred to as NES Super Mario, as he uses the sprites from Super Mario Bros. Instead of punching, kicking or using special moves, he jumps on the opponent to attack. If he gets hit, he becomes small, and if he's hit while small he instantly gets K.O.'d.
NES Super Mario is a very unorthodox character. He doesn't play like a regular fighting game character at all. His gameplay is reminiscent of Super Mario Bros. He uses the (A) button to run, the (B) button to jump and the (C) button to use a mushroom. The (B) button can be held to extend the jump's height. He cannot run by pressing or jump by pressing .
His only means of attacking the opponent is by jumping on the opponent's head. It's possible to repeatedly bounce on the opponent and rack up damage. The jump is also unblockable. He can be quite cheap because he can do a lot of damage by jumping on the opponent and it's hard to escape from. He has no Specials or Hypers and Power is completely useless to him.
When NES Super Mario gets hit, he takes damage normally from the attack, but he becomes small and gains invincibility frames. If NES Super Mario is hit while small, he instantly gets K.O.'d. However, (C) can be pressed to use a mushroom and grow large again, at the cost of 50 Life. This can be done during the invincibiliy frames after getting hit, and this can be abused to extend the amount of time the player can survive. Even when large, his size is significantly smaller than most characters, meaning other characters will often have to resort to crouching attacks.
This character has no custom A.I. and uses the engine's default. Because of the nature of the character, fights against him are incredibily awkward and unchallenging, as he walks around most of the time, leaving himself open to attacks. He doesn't jump frequently and never repeatedly jumps on the opponent. However, he will often use a mushroom after getting hit.
This character does not have any Special or Hyper Attacks.