Dr. Zed was a researcher for the Biotope Company, studying the healing spring water in the Forest of Okoya under scientists Chrom and Phossa Molybdenum. Ten years prior, Chrom and Phossa discovered the water's source at the Great Tree, sacred to a Zarude troop. They suspended research to find a respectful approach, igniting intense anger in Dr. Zed. He raged in a video log, suffered a psychotic break, and resolved to lead the company. Pursuing Chrom and Phossa in his vehicle, he ran them off the road, causing a fatal crash. Unaware they had sent their infant son, Al, downriver in a cradle with a research pendant, Dr. Zed stole their water sample and left them to die in the explosion. The infant was later found and raised by a Zarude, who named him Koko.

After Chrom and Phossa's deaths, Dr. Zed seized control of Biotope. Over the next decade, he directed aide Sharon and her teams to survey the Forest of Okoya and locate the Great Tree. His opportunity came when Ash Ketchum arrived at Biotope with Koko, who possessed his parents' pendant. Dr. Zed recognized Koko as Al Molybdenum, explained his parents' background, and falsely claimed their deaths were accidental. Scanning Koko's pendant revealed a corrupted image of the Great Tree; Koko's reaction confirmed he knew its location. When Koko refused to disclose the site and fled, Dr. Zed covertly placed a tracking device on him.

Using the tracker, Dr. Zed led a team to the Great Tree, deploying trucks and a spider-like tank. He restrained Ash and Koko with his Ariados's String Shot, imprisoning them under the guard of disguised Team Rocket members. Confirming the tree's immense energy, he ordered missile strikes to extract its power, devastating the jungle and provoking the Zarude troop. As his team doubted his methods, Dr. Zed suffered another breakdown, pleading before turning violent. He ejected the tank's pilot and took control, confessing to murdering Chrom and Phossa and dismissing Koko's survival as a "fortunate miscalculation." In the ensuing battle, he tried to kill Koko and the defending Pokémon but was defeated when Pikachu destroyed the tank's controls with Iron Tail. Dr. Zed fled, only to be cornered by Koko near a river. After a struggle, Koko trapped him with a vine as he tried to jump into the water. Dr. Zed was later arrested based on his confession and video evidence leaked by Team Rocket, showing no remorse during his televised apprehension.

Dr. Zed projected calm rationality, masking a cruel, ambitious, and unstable nature. He prioritized human benefit over ecological or Pokémon welfare, justifying the jungle's destruction by claiming the healing energy could save lives. Yet his actions centered on proving his own superiority, rejecting peaceful alternatives like extracting energy without harming the tree. He held supremacist views, deeming Pokémon unworthy of consideration, and acted with cowardice when defeated. His egomania and intolerance of criticism fueled violent outbursts, including murdering colleagues and attempting to kill an infant. Recorded evidence of his crimes, including the fatal car crash, confirmed his guilt. He showed no remorse upon arrest, glaring defiantly at cameras.

Dr. Zed commanded four Ariados, using their String Shot to immobilize opponents. During his assault on the Great Tree, he piloted a heavily armed tank, employing missiles and crushing mechanisms against the jungle defenders, symbolizing his disregard for nature in pursuit of power.