This was an enemy created by Error Weegee from a black hole. He was used to stall Mario. He can do the same things as Mario. He was defeated by a punch of the Hammer. He exploded. However, he's not dead. Error Weegee went back in time, to bring him to the present. He went into Mario's dream, and told him to wake up. He promised to help him find Luigi. He shown instructions on how to defeat a few of the army, those being Todd & Error Weegee. It was all a trick. While Mario was about to battle Error Weegee, he sneaks from behind to blast Mario. He defeated Mario in a crazy battle, but Negative Mario lost too. Geemina showed up to put an end to Negative Mario.
You're Tough, I'm Tougher
He was also able to attack Gavin, which means he became more powerful. He can also change color to make him seem like a different clone of Mario. While AGK, Yoshi, Waluigi, and Mario were searching for Obunga, Negative Mario showed up for a return. Turns out, he wanted to take over with Angry Sun. He came back to revenge Angry Sun. Error Weegee was betrayed, due to him wanting power and army to himself. Negative Mario enjoys seeing him stuck where he is. He attacked each one, starting with Mario. He whacked Mario away with a Hammer. Next he went after Waluigi. Waluigi threw a strong punch. Sadly he fell into a Portal, and fell out one to a bomb. Yoshi tried to eat him, and that failed as well. AGK threw a Bowling Ball, but he caught it. He kept trying to blast AGK, but AGK was able to attack back. It gave Mario a chance to wham back. He was defeated when Obunga hit him in the back.