Yas is the ambitious leader of the Yas Gym in Dark City, locked in a fierce competition with the rival Kaz Gym to secure the official gym designation—and the steady income that comes with it. When Ash wouldn't sign up to join his gym, Yas immediately had his recruits attack him with Pokémon to keep him from defecting to Kaz instead.
Things escalated when the two gym leaders finally faced off directly, pitting Yas's Scyther against Kaz's Electabuzz. The battle went sideways fast: Ash and his friends accidentally spilled ketchup all over both leaders and Team Rocket, and since both Pokémon have a strong aversion to the color red, they turned on their own trainers instead of fighting each other. This sent Yas and Kaz chasing after Ash, Misty, Brock, and a group of local kids.
Pikachu put a stop to the chaos with a well-timed Thunder attack. By the time Nurse Joy showed up as an official from the Pokémon Inspection Agency, everything had cooled down enough for Ash (who she knew as Tom Ato) to be assigned as the town's teacher. His first job was getting both gym leaders to work together and restore Dark City to order, which they eventually managed to do.
Content compiled by AnimeList.moe from publicly available sources.
