Gulzar is a Grass-type trainer who shows up in the Pokémon episode "Food Fight!" on Butwal Island. He's pretty full of himself—claims to be the greatest Grass-type trainer in the Orange Islands and proves it by getting angry when Tracey mistakes his flower hat for actual plants growing on his head and tries to pull it off.
When Ash steps in to defend Tracey, Gulzar takes it as a challenge and demands a battle. Things go downhill fast. Ash fumbles his Pokémon selection and ends up with Squirtle and then Snorlax, whose Poké Ball is broken. Once Snorlax wakes up mid-battle, it doesn't care about Gloom—it just wants food. The hungry Pokémon eats Gloom, Gulzar's beloved flower hat, and his entire lunch. Gulzar bails.
He runs into them again later at the island's Pokémon Center, where they're trying to get Snorlax's ball repaired. Team Rocket shows up to raid the food supplies, but Ash and Snorlax take them down. Watching Ash fight actually earns him some respect—he realizes the kid's got real skill and drops the attitude.
Content compiled by AnimeList.moe from publicly available sources.