In episode 51 ( Bulbasaur's Mysterious Garden) Ash's Bulbasaur is injured in battle against Rydon after a very strong Take Down. After being taken care of in the Pokemon Center a Bulbasaur evolutionary festival begins. The gathering is a ritual in a garden where the Bulbasaur join together so they can all evolve into Ivysaur. During this episode, once Bulbasaur gets forced out of the Pokémon Center and into the mysterious garden by other Bulbasaur, Ash's Bulbasaur is the only one who decides not to evolve even when faced by angry Ivysaur and an Venasaur. After Team Rocket try to capture the Ivysaur and the Venasaur, Bulbasaur shows his true potential by using Solar Beam against them.
During episode 56 ( The Ultimate Test) the Pokémon League entrance exam instructor has an Ivysaur.