The Fight for Equestria

Mewtwo unsheathed his sword. He was going to have fun today, especially with the robot army given to him by Sombra. He quickly directed the machines mentally, then went to his own hand-to-hand combat. After a good few minutes, the floor was covered in bodies.

So far, their resistance was strong, so there wasn't an immediate takeover of the palace, but he would get there eventually. Then he saw him. It surprised Mewtwo to see him, and wasn't prepared. I mean, it was kinda difficult before to take out a spartan before, and based on the fact he survived, it may become even more difficult.
Meh, who cares?

Then Mewtwo was jabbed in the back what felt like the nose of a rifle. He let out a surprised, painful cry. But he recovered quickly. He turned and rested his hand on the rifle and tried to move it from his back, but was stopped by a strong hand. He glanced at the hand, and realized who he had engaged in combat with, and reconsidered his options: telepathy.

Mewtwo sent Master Chief flying into a nearby wall, crumbling under the impact. But he just got back up and charged at him again, this time a pistol in his hands. Mewtwo moved the pistol from his hands and threw it across the room, then attempted a mind-fry on him. It failed, which meant he had a Psy-Screen, which can deflect psychic waves. Mewtwo turned his sword to the charging superhuman. It would work.

Then he was gone. "What the hell" was all Mewtwo could say before being pushed to the ground. He had been jumped over. "Listen, you're under arrest and coming with me," he told him, "or else you'll die by punch." Mewtwo knew he would've, so he teleported out of the man's grasp and began to stab him when the man as engulfed in a cloud of black and blue. Nightmares.

Nightmare Moon had come to his aid. She forced the man to start screaming in fear and thrashing all over the floor.
The man then fell asleep, which Mewtwo hoped would remain. In the meantime, all Mewtwo needed to do was find and capture the Princess of Friendship, and he had won. Mewtwo took a quick look around the large meeting room and found nothing. He quickly conveyed a message to the machines telling them to begin looking outside the room and into the heart of the palace.

But he quickly canceled that when he saw not just the Princess, but five more ponies to take as Prisoners of War. They were levitating across the room with rainbows going about them. The turned toward him. He knew what was coming.