Twilight Sparkle Edit
Donatello is walking in the sewers. Then Twilight Sparkle teleports in front of him. They get in battle poses.
Donatello runs at Twilight Sparkle to hit her with his bo, but Twilight Sparkle teleports behind him and bucks him in the back, making him crash to the ground. She flies above him and tries to land on him, but Donatello rolls out of the way. Donatello gets up. Twilight Sparkle fires magic at him, but Donatello jumps up, making the magic hit a wall. He tries to hit Twilight Sparkle with his bo again, but Twilight Sparkle teleports away again. She then teleports in the sky. She then fires a huge blast of magic down at the ground. A massive hole in the ground is formed and Donatello is obliterated. Twilight Sparkle flies away, victoriously.
Twilight Sparkle had the advantage in magic, flight and teleportation. While Donatello and the other Teenage Mutant Ninja Turtles fought tough enemies, so has Twilight Sparkle. Also, considering that the force of a horse's kick is between 1,500PSI and 2,000PSI, Donatello would be severely injured and possibly die.
Winner: Twilight Sparkle