From Bulbapedia, the community-driven Pokémon encyclopedia.
Kaz (Japanese: カズ) is a character of the day featured in Showdown at Dark City. He was not given an English name in the dub.
Kaz's goal is to get his Gym recognized as the only official Gym in Dark City in order to make money. He therefore has a bitter rivalry with the other would-be Leader, Yas. To this end, the two Leaders and their pupils have been battling constantly, much to the detriment of the residents of Dark City.
His dreams of wealth through leading an official Gym are dashed by a disguised Nurse Joy, who, acting as an official representative of the Pokémon League, declares both him and his rival unfit to be Gym Leaders.