Prior to the start of the Black 2 & White 2 chapter, Dewott was one of the many Pokémon in the International Police Headquarters. One day, Blake was summoned by the Chief of Police to pick out a Pokémon due to not having one despite passing all his exams. Blake claimed not having a Pokémon isn't a problem, as he would rather wait to find one that matches his skills. Quickly after saying this, he noticed Dewott in the back polishing his scalchops and picked him as his partner.
Dewott first appeared in The Transfer Student, where he was standing beside Blake as he was breaking up with Yancy. He later battled in Blake's school tournament and easily advanced Blake to the finals. During the finals, he battled Hugh's Trapinch, defeating it with a Razor Shell. Being the winner, Blake received a Pokédex. Later that night, he helped save Looker from a Scolipede, defeating it in one hit.
In Flying Type, Dewott battled a Genesect sent by Team Plasma. Dewott started off with a powerful Razor Shell, but Genesect took it head-on with little damage. Genesect then charged at the group and Blake jumped on top of it. Using his International Police Arm #15 Record Bubble, Blake sent a message to Dewott, telling him to attack Genesect like he attacked Scolipede, but to use both scalchops instead. Dewott followed his command and went on the offense against Genesect, forcing it to bring out its cannon in order to counter-attack. Genesect then fired its cannon, destroying one of Dewott's scalchops. Despite the loss, Blake was able to find the person controlling Genesect due to Dewott's attacks. After confronting the man, he had Genesect attack Blake with Techno Blast, knocking him off the building they were on. Dewott managed to save Blake, and they ran away to come up with another strategy.
Blake soon figured out that Genesect was not owned by Colress and decided to capture it. While trying to capture it, Dewott began attacking it to wear it down. During the battle, Dewott inserted a scalchop into Genesect's drive, and when Colress attempted to switch out its cartridge for another one, it got stuck, allowing Dewott to attack with Aqua Jet. Before he could get there, however, Colress removed it and switched the cartridge. Genesect then hit Dewott with an Electric-type Techno Blast, dealing major damage. During the confusion that followed, Blake hid Dewott with his International Police Arm #2 Invisible Cloth and captured Genesect, forcing Colress to flee.
In Legendary Tornadus, Dewott battled Team Plasma's Tornadus at Route 20. Quickly after the battle started, Tornadus changed into its Therian Forme. After Tornadus dodged a Razor Shell, Blake realized that the Tornadus was faster than his Genesect, and had Dewott try a faster Aqua Jet attack, combined with Dewott's scalchop. With Tornadus still able to evade the Discipline Pokémon's attacks, Blake sent out Kelden to assist Dewott in the fight. Tornadus then focused on capturing Giallo, while Dewott and Kelden worked together to overwhelm the Cyclone Pokémon. To prevent Tornadus from escaping, Blake had Kelden use Icy Wind, followed by Dewott's Razor Shell, freezing it solid. With Tornadus frozen, the Team Plasma Grunts retreated, returning Tornadus to its Poké Ball.
In Therian Forme III, Blake sent out Dewott to battle Colress and Tornadus at Driftveil City. Tornadus blocked Dewott's attacks, allowing Colress to run away with a captured Zinzolin. Not wanting to let his targets get away, Blake had Dewott battle against Tornadus while he chased after Colress. Though Dewott proved to be a powerful opponent, he, Glisott, and Kabutott were eventually defeated by the Shadow Triad and the Forces of Nature. In Deduction Time, Dewott was found unconscious by Looker, who returned him to Blake in The Final Battle: Crushed Ambition.
In The Final Battle: Crushed Ambition, Dewott worked alongside Glisott and Kabutott to track down Colress's Beheeyem, which was carrying a new version of the Colress Machine. With Kelden's help, the four were able to corner the Cerebral Pokémon and destroy the machine. After the battle, Dewott worked alongside other Water-type Pokémon to try and put out the fire on N's Castle. When that proved to not be enough, Dewott, alongside the other eight Unova starters, fired their Pledge moves at the castle.