Leonardo (clone) appears in the live action series, Ninja Turtles: The Next Mutation.
On orders from Dragon Lord, Cornelius Quease sets about collecting DNA from each of the Turtles, which he will use to create clones of them. The Leonardo clone is the third of the clones to be created. Quease’s robot sneaks into the Turtle Lair to snag the coil of dental floss that the real Leonardo had used earlier and then dropped on the floor. Quease uses the DNA from the floss to make the Leonardo clone.
After one full clone team has been created, Dragon Lord wants Quease to grow an army of mutants for him. Once that army is complete, Dragon Lord will himself be mutated into what he terms as “a glorious dragon deity”.
Each clone is fitted with a Mega Spinal Thermostat which is attached to the upper part of their carapace. A coiled cord runs up from the Thermostat to the back of their head. Dr. Quease uses the Mega Spinal Thermostat to control the clones. Using a special tool, he can adjust the thermostats to flood the clones’ veins with rage endorphins.
During a fight in Quease’s laboratory with the real Turtles, Donatello manages to spin Leonardo clone around several times. While his back is turned, Donatello yanks the Thermostat device off of his carapace, incapacitating the Leonardo clone.