Newtralizer is a mutated Fire-belly Newt. He is intelligent (though incapable of speech) and can operate a daunting array of weapons, including lasers, missiles, sawblades, and exploding mines. He can catch and constrict a foe with his tail, which typically sports a pair of blades. Apparently, he has a voracious appetite and can consume a whole (unarmored) Kraang. He possesses incredible strength, speed, and durability. Even without his armor, he is able to withstand attacks from numerous Kraang lasers, Leo's katana, and Raph's sais.
Newtralizer was accidentally released from his Kraang cell by Donnie and went on a rampage against the Kraang and the Turtles. He was crushed under a car by Mikey but emerged alive and unharmed.