Kit first appeared as a Lickitung in Licking Lickitung, having stolen Diamond's food and Town Map. Attempting to recover it, Diamond ran into the Pokétch Co. President, who insisted he help advertise his Pokétch. While advertising, Lickitung showed up again in an attempt to grab more stuff, and Diamond decided to capture him. Lickitung attacked Don with Rollout and followed up with a Slam, allowing Don to throw Lickitung. This enraged Lickitung and caused him to evolve into a Lickilicky. Diamond then attempted to capture him, but only ended up upsetting him more. Lickitung then burrowed underground and began attacking with Dig. Using his Pokétch Diamond figured out where Lickilicky's next spot to attack was and had Lax grab him when he surfaced. Diamond then threw a Poké Ball at him, capturing him. Afterward, the two went around town and returned all of Kit's stolen items.
In Yikes, Yanmega!, Diamond ran into a group of Yanmega being controlled by Mars that were attacking Roseanne. After assessing the situation, Diamond had Kit attack with Power Whip to scatter them and find the device that is controlling them. Diamond then had Tru attack with Razor Leaf, but the attack missed, surprising Diamond. Due to this, he and Kit go straight into the middle of the swarm and take one of their attacks head-on, allowing Kit to grab the device and smash it. Due to the device being destroyed, the Yanmega are left without instructions and leave.
In Mixing It Up with Machamp, Kit was separated from Diamond, alongside Tru, at Lake Verity after falling from the Galactic airship. They were later taken to Pearl by Sebastian. In Chancing Upon Chingling, once Diamond was spotted by the Advanced level Grunt, Chatler returns Kit and Tru to Diamond. Kit then participated with Diamond's other Pokémon to battle against the Advanced level Grunt but proved to be no match for his strength.
In Double Trouble with Dialga and Palkia VI, Kit was used alongside the other Pokémon to battle against the Legendary Pokémon Dialga and Palkia. With the help of Diamond and Pearl's Pokémon and with a combined technique, they were all able to destroy the Red Chains controlling them.
In Unplugging Rotom (Heat, Wash, Mow, Fan, Frost), Kit battled a wild Rotom that Diamond and Pearl were trying to protect. Diamond sent out Kit to battle against it and had him attacked with a Slam attack alongside Digler's Earthquake, but the moves dealt no damage due to it being an Electric/Ghost type and having the Ability Levitate. Rotom then moved towards Diamond and Pearl and shocked them while giggling before leaving for Eterna City.
In The Final Dimensional Duel VIII, Kit helped alongside Cyrus's Honchkrow to free Dialga and Palkia from Giratina's trap. Kit used Me First to copy Honchkrow's Night Slash in order to cut away at their restraints.