While Ash and his friends were heading through Trovitopolis on the way to Trovita Island, they landed in the sewers after one of Team Rocket's attempts to steal Pikachu went wrong. The Trovitopolis Officer Jenny found them down there after Ash's Bulbasaur got kidnapped by a creature. After Ash and his friends got out of the sewers, they were locked in jail. The paranoid mayor wanted to get rid of the creature in the sewers to improve his chances in the next election, and hired a personal SWAT team to carry out his needs by guarding every sewer entrance in the city. However, after sealing all the exits in the sewers, it turned out the mayor cared more about winning the next election than what was going on down below, emphasizing his selfish, egocentric, power-hungry and cruel nature.
As Ash and his friends were looking for Bulbasaur, Misty and her Togepi were captured, too. It later turned out aBulbasaur that was twice its normal size was the creature wreaking havoc. It was driven by loneliness, having been abandoned by the mayor when he was a child, and was looking for someone to keep it company. Ash, Misty, and Tracey then showed the whole town that the monster was the Bulbasaur that the mayor abandoned, after the pipes burst and flooded Trovitopolis City Hall.
The mayor revealed the fact he abandoned the Bulbasaur because it wouldn't evolve. After hearing what happened, the townspeople realized the mayor had been lying the whole time and refused to vote for him. He was put away, and the town's Nurse Joy agreed to take care of the Bulbasaur.