Like Donatello, Shellectro is a technical genius who provides the mechanical assets for his team, including a highly-advanced computer with encyclopedic information on super villains, holographic training simulators, and intricate cellular scanners.
Along with his brothers, Shellectro was once trained by Sliver until their master became evil.
Shellectro was first seen in a training simulator where he and his brothers - Blobboid, Griddex and Graviturtle - were battling holographic robot monsters. When interrupted by Michelangelo, Shellectro was baffled by the existence of this strange Turtle and unsure what he was talking about.
He used his technologically-advanced machinery to scan Michelangelo's body, confirming that he had no superpowers. He discerned that Michelangelo had large amounts of residual chronal energy in his cells, which caused him to periodically flux out of that reality. Before Shellectro could learn more, Mayor April O'Neil arrived with news that Sliver was preparing to annihilate all life on Earth with the Penultimate Nullificator.
Shellectro and his brothers set out to Sliver's tower to stop him, but they were imprisoned in a cage of Utromidium, which nullified their powers. Once Michelangelo and Blobboid managed to free them, Shellectro used his electrical and technical powers to reprogram the Penultimate Nullificator to only destroy the tower and everything inside it, and flew out of the building with other Super Turtles.
Later he was present when a statue of the "Turtle Titan" was erected.