Colress debuted in Team Plasma's Pokémon Power Plot!, conducting experiments with wild Pokémon in an attempt to bring out their true strength. From his base in an abandoned observatory outside of Floccesy Town, he used a large machine to generate electromagnetic waves that resonated with small devices on the wild Pokémon's foreheads, increasing their aggression and attack power while also rendering them subservient to Team Plasma's commands. Unfortunately for the villains, the mind-control device's EM waves also leaked into the surrounding wilderness, driving the local Pokémon to attack Floccesy Town and revealing their presence in the area. When Ash, his friends, and Looker arrived in the observatory, Colress released his mind-controlled Pokémon on them to test their strength. Impressed by their Pokémon's ability to match his brainwashed Pokémon, he planted one of his controlling devices on Pikachu, forcing him to fight his Trainer. However, Ash's encouragement allowed Pikachu to fight against the EM waves, eventually causing the device to break and freeing Pikachu, much to Colress's amazement. Before he could gather further data, Team Rocket showed up, using one of their miniature robots to steal Colress's research data from his computer before quickly reciting their motto and making an escape with their balloon. With the mind-controlled Pokémon freed, Colress and the Team Plasma Grunts he had with him retreated, destroying the observatory with a self-destruct mechanism to get rid of all possible evidence.
Colress appeared again in Team Plasma's Pokémon Manipulation!, where it was revealed that he had upgraded his Pokémon-controlling machine with his remaining research data. Instead of emitting radio waves to activate separate receivers on its targets, the machine now fired a narrow energy beam which instantly brought any Pokémon it hit under Team Plasma's control. Using this machine, Colress took control of a Haxorus, which he sent rampaging in a city. When Ash and his friends arrived and sent their Pokémon to stop Haxorus, Colress used his machine to take control of Iris's Dragonite, giving the heroes a lot more trouble to deal with. Suddenly Team Rocket appeared, attempting to steal Colress's machine. A battle between Jessie and James's Woobat and Amoonguss and Aldith's Liepard then took place, during which one of Liepard's Shadow Balls accidentally hit the machine, breaking it and freeing Haxorus and Dragonite from his control. Realizing that they were at a disadvantage, Colress and the Plasma Grunts retreated.
Colress appeared briefly in Secrets From Out of the Fog! with Aldith, discussing Team Plasma's plans with Ghetsis on a videophone call.
Colress appeared again in Meowth, Colress and Team Rivalry!. Team Rocket invaded his newest laboratory and drew his security - consisting of Aldith, Barret and some other Plasma Grunts - into a trap in the woods. Once Colress was alone, Meowth approached him and attempted to convince him to join Team Rocket. Colress refused, but offered to allow Meowth to participate in an experiment to increase his strength. Meowth agreed, having undergone training to resist the mind control device. However, Colress still managed to take control of Meowth, and ordered him to attack Jessie and James. Using Frillish and Amoonguss, they managed to snap him out of it before escaping. Later, Colress was seen with his Grunts reporting to Ghetsis, who revealed information about the Light Stone to them.
In Ash and N: A Clash of Ideals!, Colress appeared with the rest of Team Plasma to commence their operation at the White Ruins. While Aldith, Barret and many other Grunts ambushed the workers at the site, Colress used his perfected machine to seize control of the workers' Pokémon and turn them on their Trainers. In Team Plasma and the Awakening Ceremony!, he also took control of Pikachu again, forcing N to surrender the Light Stone to Team Plasma in exchange for Ash's safety. He appeared again in What Lies Beyond Truth and Ideals!, aiding Ghetsis in taking control of the awakened Reshiram. When Ash and Pikachu tried to stop him, he used his machine on Pikachu yet again. However, this time Pikachu was able to fight against its control, and - together with Reshiram - destroyed Colress's machine once and for all, thus freeing the controlled Pokémon. Later Colress and the other Team Plasma members were arrested by Looker, thus bringing the team down. As Officer Jenny took Team Plasma into custody, Colress mentioned his next project will be a device that allows Pokémon to communicate with people.