Ryuuta

McCauley is a character of the day who appeared in A Chip Off The Old Brock.

McCauley works with Katie and Mariah at a pharmacy where they make medicines using electricity. He was having a hard time getting the potions right. He would stay up late at night with his Ampharos just trying to perfect his technique. He had always striven to be as good as Katie, ever since he and Mariah were little. Katie explained that McCauley needed to have more confidence in himself.

Later, Mariah got taken away along with the whole pharmacy by Team Rocket, who wanted all the medicine for themselves to sell. McCauley jumped into the flying pharmacy in order to save her and the medicine. Brock, who had been invited by Katie to the shop earlier along with Ash, May and Max, attempted to help out by using Marshtomp's Mud Shot to shoot down the balloon. However, Team Rocket managed to reflect it back. The Mud Shot ended up hurting Ash's Pikachu and Katie's Mareep. They quickly needed a potion to make them better. Both McCauley and Mariah decided to use their Ampharos and Flaaffy, respectively, to make a new batch of medicine from the remaining ingredients, and they succeeded. Afterwards, they used their Pokémon to destroy the engines on Team Rocket's balloon, causing it to crash.

After Team Rocket was defeated, Katie felt confident enough to leave the pharmacy to McCauley and Mariah.

(Source: Bulbapedia)