Tracey Sketchit (Kenji) is a Pokémon watcher who takes Brock's place during the time he spends with Professor Ivy.
Tracey is a talented sketch artist and is often seen sketching Pokémon while on his journey with Ash and Misty. He considers himself a "Pokemon watcher," much like Professor Oak who watches and studies Pokémon. Whenever the group find a town that has a new Pokémon or new tradition that has to do with Pokémon, Tracey always makes the group stop and stay so he can sketch it.
When the group returned to Pallet Town after their adventures, Tracey learned that he would be meeting the "great" Professor Oak. This made Tracey nervous and shaky because he thought of Professor Oak as the most knowledgable and greatest professor in the world. He even spent several minutes sorting out his sketches so he would see which ones Professor Oak would like. When he finally met Professor Oak, he gave him all of his sketches and watched him intently to see what his reaction was. At the end of the episode, Professor Oak revealed that he loved Tracey's sketches and thinks that he is a wonderful artist. Tracey then told Ash and Misty that he would no longer be traveling with them and that he would be staying with Professor Oak and become his pupil from now on. Ash and Misty were shocked and saddened for a moment because they wanted Tracey, to join them and Brock through Johto, but it was understood that was what Tracey wanted.
Since then, Tracey usually makes appearances whenever Ash visits Pallet Town or calls Professor Oak.