In Grass Hysteria!, May was kidnapped by a hungry Skarmory and ended up lost in a reserve for Grass-typePokémon called the Forbidden Forest. There, she met Venusaur, then a clumsy Bulbasaur, while she was trying to pick flowers. Bulbasaur warmed up to May after being saved from a fall, but the other Pokémon in the reserve repeatedly tried to attack May. However, Bulbasaur explained to Venusaur, her parent and the ruler of the Forbidden Forest, that May was a friend. Before May had to leave, Bulbasaur decided to stay with her.
In Hokey Poké Balls!, May sent out Bulbasaur to enjoy the sights as they went through a city. Bulbasaur quickly got distracted by some flowers in a truck and had to be rescued as the truck sped off. Later, at the Pokémon Center, May showed Professor Oak her Bulbasaur, which made Ash decide to bring his own Bulbasaur over for a visit. When the Poké Ball arrived, it wouldn't open, making everyone believe that the Pokémon Center's Balls were stolen. The culprits were revealed to be Team Rocket, who accidentally dropped Ash's Bulbasaur while escaping. The two Bulbasaur teamed up to stop Team Rocket. Once they found Team Rocket, the two Bulbasaur battled them, with Ash's Bulbasaur protecting and teaching May's how to fight. After rescuing the Pokémon, Professor Oak called back and asked for Ash's Bulbasaur to return so it could stop the Water and Grass Pokémon from fighting. Ash sent his Bulbasaur back to Professor Oak's Laboratory as May's Bulbasaur appeared to have made a positive change from the experience.
Bulbasaur also competed in the Battle Round of the Hoenn Grand Festival. In Rhapsody in Drew, she was called out to battle along with Beautifly against Harley's Cacturne and Banette. Together they managed to defeat their opponents and advance May to the next round.
In The Right Place and the Right Mime, Bulbasaur was one of the Pokémon May decided to bring with her when she traveled through the Kanto region. Bulbasaur reunited with Ash's Bulbasaur when May made a stop at Professor Oak's Lab to meet up with Ash. The two Bulbasaur were later used in a battle against Team Rocket, where May's Bulbasaur was impressed by Ash's Bulbasaur's skill. May decided to leave Bulbasaur at Professor Oak's Lab so she could learn more from Ash's Bulbasaur. Eventually, after journeying to the Johtoregion, May got Bulbasaur back from Professor Oak, and during her time away from Ash, she evolved twice, into Ivysaur and Venusaur.
As a Bulbasaur, she proved to be a very sweet Pokémon. She was very willing to compete in Contests and do the best she could. She was very confident in most of her Contests. The only exception was her first Contest, in which her nervousness showed in her performance.
She was distinctive from Ash's Bulbasaur in three ways: she had a gentler personality, a pair of heart-shaped spots on her forehead, and she was able to use the move Petal Dance as opposed to Ash's Bulbasaur's use of the technique Solar Beam.
It is unknown whether she still holds on to these traits after her evolution.