Ash and his friends met up with Zachary while on their way to Ecruteak City. When they met him, he was in the middle of some problems. His Yanma would always break the windows of the stores of the town where he lives, by beating its wings. The town was furious by the Bug Pokémon's actions, and Mr. Evans made his son get rid of it. Zachary became upset, remembering that he found it one day during a storm. He released it, but after realizing what he had done, he ran off to find it.
Unfortunately, Team Rocket found it first, and were using it to break windows. Seeing Yanma with them, the town assumed that Zachary was with them. But he proved them wrong by defeating the trio with his Yanma. The town forgave Zachary, who successfully trained Yanma not to break store windows. Everything then went back to normal.
Yanma was found injured in the rain by Zachary, when he and his father were walking home. They took it home and nursed it back to health, but when it got better, Yanma became a problem. It couldn't control the sonic aspect of its wings and broke nearly every window in the town, angering the villagers. Mr. Evans told Zachary he had to return it to the wild, and Zachary had no choice but to agree. He left food in the woods for Yanma to distract it, and Zachary ran off, leaving Yanma behind.
Yanma was then found by Ash and his friends. It stole Ash's hat, but once Ash got his hat back, it flew off. Yanma then tried to look for Zachary when Team Rocket suddenly found it and trapped it with the intention of using it in one of their evil schemes. They shattered all of the windows in Zachary's hometown and then created their own window company at the same time, profiting immensely off the destruction they caused.
They were about to repeat this scheme when Ash, his friends, and some townspeople spotted them. Team Rocket threatened to smash the stain glass window in the Pokémon Center, so Ash and Misty could not battle them. Zachary then decided to return Yanma back into its Poké Ball, which worked. Ash and Misty's Pokémon were hurt in the resulting battle, so Zachary used his Yanma in its first battle ever, sending Team Rocket blasting off. In the end, Yanma was able to control its wings during a Sonic Boom attack.