Keita

Keith is a character of the day in So Near, Yet so Farfetch'd.

Along with his Farfetch'd, Keith stole Pokémon from other people and used them for his own. He would have his Farfetch'd distract his victims so he could swipe Trainers' backpacks and replace them with backpacks filled with rocks. Misty, Jessie, and James were three of his victims. When Ash, Pikachu, Brock, and Misty reported to Officer Jenny of what happened, Jenny stated that Misty was Keith's fifth victim. Jenny had been after him for a while, but he never seemed to stay in one place.

Psyduck, after escaping from Keith without him knowing, found Ash and his friends and led them to Keith. After catching Keith, he explained the reason why he had been stealing—he thought his Farfetch'd was too weak to battle. However, Farfetch'd proved to him that it could battle by defeating Ash's Bulbasaur. Misty's Psyduck later defeated Keith's Farfetch'd with its Disable. After Team Rocket dumped a bunch of Voltorb that he had given to them from their balloon, he decided not to steal Pokémon anymore and returned the Pokémon to their rightful Trainers. Because of this, Jenny told him that none of the victims would press charges against him. After learning his lesson, he decided to train his Farfetch'd in catching Pokémon, rather than stealing them.

(Source: Bulbapedia)