Reuniclus, as a Solosis, made her debut in Going Solosis! She had a brief battle against Nate's Turtwig, which ended once she incapacitated him with Confuse Ray. Nate, determined to catch her, followed her into a nearby forest. Using her psychic powers, Solosis showed Nate a vision of poachers attempting to capture her. When Kai turned up to try and steal Solosis once again, Nate protected her, thereby earning her trust. Once Kai had been sent on his way, Solosis expressed a desire to join Nate's team and he caught her.
In Pokémon - The Musical!, Solosis performed in a Pokémon Musical along with the rest of the group.
She was briefly sent out to battle Colress in The Science of Battle! Her Confuse Ray failed to affect Colress' Grumpig due to its Own Tempo Ability and she was defeated by Dark Pulse.
In The Dynamic Duosion!, Nate sent Solosis out to battle a Trainer's Kadabra. However, Solosis refused to battle and was defeated easily by Kadabra. After being taken to the Pokémon Centre, Solosis evolved into Duosion as means of healing herself. Upon evolving, Duosion became very determined to battle Kadabra and get her revenge. Nate and Duosion then trained together into the night and battled Kadabra again the next morning. Using her newly-learned Psyshock, Duosion defeated Kadabra.
Duosion was used to battle several Team Plasma grunts on the Plasma Frigate in Ship Shape Rescue Mission! and Battle in the Open Skies!, alongside Turtwig and Magnemite.
She was used to stop Lewis' newly evolved Krokorok's rampage in Getting Up on the Wrong Side of Evolution!, using Confuse Ray to immobolise it.
Duosion was used by Nate to battle Colress in Set Sail for Danger! and A Liepard Once Lost!. It defeated Colress' Kinklang.
In Genesect's Awakening!, Duosion was used to battle Colress once again, this time against the scientists' ultimate scientific breakthrough: a Genesect. During the battle, Duosion evolved into Reuniclus. Despite her increase in power, Reuniclus was unable to put up much of a fight against the Mythical Pokémon and Colress stopped the battle.
Reuniclus, as a Solosis, was shown to be a relatively pacifistic Pokémon, preferring to stop her opponents using Confuse Ray rather than using attacks. She also showed the ability to create illusions in order to trick her opponents, further demonstrating her lack of interest in conventional battling.
However, after evolving into Duosion, her personality changed completely. She became much more interested in battling and wanted a rematch with the Kadabra that had beaten her immediately. Duosion formed a deeper bond with Nate during the night they spent training and was able to battle very well, despite it being the first battle she participated in properly. This bond and personality was retained when she evolved into Reuniclus.