Bulbasaur is frequently viewed as the responsible leader of Ash's Pokémon, especially due to his actions at Professor Oak's lab. It is also a Pokémon Ash values more than most of his other Pokémon, possibly because he always wanted to catch one, as explained in Bulbasaur and the Hidden Village, although it was his second choice as a starter, after Squirtle. It also formed a bond with Pikachu and Squirtle while they fought together while part of Ash's team. But, at the start he disliked trainers as shown in Island of the Giant Pokémon where it said, "Maybe Ash has forgotten about us".
Bulbasaur's best friend in the group is Squirtle, who's immature, fun loving personality contrasts with Bulbasaur's serious, mature one. Nonetheless, all of Bulbasaur's immature acts have something to do with Squirtle, such as Bulbasaur angrily chases Squirtle after it accidentally ate its cookie, or using Squirtle as a sled after witnessing other Pokémon enjoying themselves on actual sleds.
Both Bulbasaur and Squirtle are always seen teaming up together when they compete against Snubbull and his group during summer vacation and throwing snow balls on Pikachu during winter vacation. When Squirtle was leaving, Bulbasaur looked away while shaking hands/vines, sad to see its friend go. However they briefly reunited together during the Silver Conference and both also gain a bitter rivalry towards Jackson's Meganium and Azumarill who makes fun of both of them.
In Hokey Poké Balls, Bulbasaur also became friends with May's Bulbasaur when they briefly play together and he teaches her how to handle against James' Cacnea and Jessie's Seviper after she was unable to negate their attacks and later they work together to knock them down with their Vine Whip as the two are later seen doing a Vine Whip high five. Bulbasaur finally stays with May's in the later episode The Right Place and the Right Mime so that May allows her Bulbasaur to stay at Oak's lab to learn more from Ash's until she evolves twice in her evolutionary stage.
Ash's Bulbasaur resides at Professor Oak's Pokémon Lab , and constantly acts as a peacemaker and an ambassador between the rest of the Pokémon who were Grass-type and Water-type.
Bulbasaur was raised in the Hidden Village by Melanie, who cared for sick, injured, and abandoned Pokémon. Bulbasaur acted as the village's bodyguard, but after Ash helped defend the Hidden Village from an attack by Team Rocket, Melanie encouraged it to join Ash, explaining that its growth was being stunted by staying too long in the village. Although Bulbasaur initially appeared to distrust Ash, it agreed to join him. In Island of the Giant Pokémon, it alone assumed that Ash had abandoned it and the others. Its views on Trainers were presumably colored by all the abandoned Pokémon in the Hidden Village. Over time Bulbasaur grew to trust its new Trainer.
Bulbasaur is extremely stubborn, surly, and eager to battle. Although its surliness has lessened. It battled against Erika's Tangela and lost, but redeemed itself when battling against Aya's Venonat, where it sent Stun Spore back at it by blowing at it and beat it with Leech Seed. It had the opportunity to evolve after battling a powerful Rhyhorn with a very strong Take Down attack in Bulbasaur's Mysterious Garden, but refused at a mass of Ivysaur as well as a Venusaur because it doesn't want to evolve at the Bulbasaur evolutionary festival. This allowed it to learn the powerful Solar Beam technique. Venusaur finally understood, but Ash said that Bulbasaur will evolve if it wants to.
It has the heart of a fighter and it never gives up in a battle. It has the determination to keep fighting even if the odds are against it, defeating such varied opponents such as a herd of Exeggutor, despite the disadvantage. It also beat Jeanette Fisher's Beedrill with Tackle, and went on to battle Scyther despite the type disadvantages. After some trouble, he used Vine Whip to hit every Double Team clone and then hit the real Scyther with both vines knocking it out. Ash tried for the sweep with Bulbasaur, but he fell to her surprisingly strong Bellsprout. On one occasion Bulbasaur, along with Pikachu, was briefly lent to Misty to allow her to compete in the Princess Day Festival with a more balanced team, Bulbasaur single-handedly winning her first match by defeating a Kingler, Pinsir, Cubone and Raticate on its own.
Bulbasaur was also used to battle against Drake, the Orange League Champion, and his Electabuzz. Bulbasaur is undamaged by Thunder Shock and hits it with Razor Leaf. Bulbasaur then lands a Tackle, but is knocked out by Thunder Punch.
Bulbasaur was used to capture Heracross, who started sucking sab from its bulb, much to his annoyance. Bulbasaur became the only member of Ash's original team, save for Pikachu, to remain in his care, while it watched its best friend Squirtle and companion Charizard leave.
It battled against a wild Chikorita that Ash wished to capture. It was also used to fight Team Rocket, but was annoyed by Heracross, who was sucking the sap from his bulb. It was also used to battle Misty to decide who gets to keep Totodile. Bulbasaur looked set to beat her Poliwag with Razor Leaf, but it evolved into Poliwhirl and hit it with Bubble. Bulbasaur then flattened Poliwhirl with Solar Beam, winning the match for Ash. It also had a rematch with Aya and crippled it with Leech Seed once more, but this time, Venonat came back and almost won with Supersonic and Tackle, but Bulbasaur knocks it out with by throwing it with Vine Whip
Bulbasaur had stayed with him until midway in the Johto adventures in the episode, Bulbasaur... The Ambassador!, when it was sent back to Professor Oak's to keep the Pokémon there from quarreling with each other. When Bulbasaur was mauled with both grass and water-type Pokemon while Tracey's Marill, Venonat and Scyther to stop them. The fight stops when Bulbasaur unleashes its Solar Beam as the two wild Bellossom does a peace dance. Bulbasaur serves as a peacemaker of both water and grass-type Pokemon and seeing their quarrels because of the dispute of the Water-type Pokemon lake. It decides to make a new lake for Grass Pokemon by digging and it also convinces a wild Poliwhirl to wash the ground with Water Gun and three Sandslash to Dig. Once the lake is already made, it saved an Oddish from a falling boulder, as both water and grass Pokemon are saddened thinking it was killed and Bulbasaur was revealed to be alive by using Dig. Professor Oak convinces Ash to keep Bulbasaur at his lab to serve as its peacemaker which Ash agrees. Bulbasaur is last seen watching stars knowing that he will miss Ash, Pikachu and its friends.
Bulbasaur came back alongside its friend Squirtle in the Johto League, where Squirtle was mocked by Jackson's Azumarill, as well as being slapped in the face. Bulbasaur calmly restrains them, but the better half of the duo joins the fray when Jackson's Meganium mocks it. He battles against Jackson's Magneton, who had defeated two of Ash's Pokémon in the 3-on-3 match. Bulbasaur learned from Pikachu and Cydaquil's mistakes, and despite being the most disadvantaged one out of the three, he takes the win with Leech Seed and Vine Whip. He then battled against Meganium, who he still had a bitter rivalry for the pride of Grass-type Pokemon. Despite Bulbasaur being tired from the previous battle while Meganium is healthy, Bulbasaur dodges Body Slam an lands a Razor Leaf, while being hit by Meganium's Razor Leaf. It reverses its Body Slam by using Vine Whip around its neck and pelts it with Razor Leaves and Vine Whips, before a double Solar Beam takes them both out, resulting in a tie for the two trainers, and Ash advancing to the next round.
Advanced Generation Series
Bulbasaur continues to reside at Professot Oak's lab along with Ash's Bayleaf, Cyndaquil, Totodile, Noctowl and the rest of the Pokemon in the episode, Showdown of the Oak Corral, where they discovered that both Golem and Nidoqueen are actually Butch and Cassidy in disguise to steal all the Trainer's Pokemon. Professor Oak chooses Bulbasaur to fight off Butch's Hitmontop which it defeats it with Vine Whip while being assisted by Tracey's Scyther. After defeating their Pokemon, Bulbasaur hits them hard with Solar Beam until Totodile blasts them away with Hydro Pump. Bulbasaur later continues to watch over in Professor Oak's lab along with Ash's other Pokemon.
In Journey Through the Starting Line, Bulbasaur does its best to stop all of the Tauros from getting stampede but failed and they bust in Professor Oak's lab but all of the little starter Pokémon ran away. Bulbasaur also does not impressed on the town mayor's son, Gilbert who likes to pick all of Professor Birch's starters rather than they are from Kanto. After Tracey finds Charmander in the river stream, Bulbasaur was aided by Professor Oak and Gilbert and they saw Squirtle is about to fall off. Due to Gilbert's arrogance and wants to leave, he falls into the edge but was saved by Bulbasaur with its Vine Whip while Professor Oak catches the falling Squirtle in time. By the time to find a little Bulbasaur who is trying to avoid getting pummeled by several Primeape. Delia let Mimey use Psychic to keep Bulbasaur safe until it was disrupted by Gilbert who sneezes causing them to be chased by it. Both Gilbert and the little Bulbasaur ends up in a cliff, they are rescued by Ash's and puts them to safety and faces all of the Primeape. Bulbasaur scares them by shooting a Solar Beam much to Gilbert's amusement and it scares all the Primeape away in fear.
Because of Bulbasaur's bravery, Gilbert finally chooses the little Bulbasaur as its starter Pokémon and it watches Gilbert leave to start on his journey with the little Bulbasaur as his partner.
Bulbasaur later returned in Hokey Poké Balls to meet May's Bulbasaur, after it manages to catch Bulbasaur's Poké Ball with its Vine Whip after they failed to catch Team Rocket and the two Bulbasaur quickly became friends. Both Ash and May's Bulbasaur are teaming up to find the missing Poké Balls which are stolen by Team Rocket. When James activates the cabin into a large steel guard building, May, Max along with two Bulbasaur manage to get through the roof as their Vine Whip are used to get what's stolen. Pikachu manages to knock through the wall with Iron Tail. Cornered, Jessie and James uses Seviper and Cacnea to attack May's Bulbasaur who is unable to negate their attacks even her Razor Leaf. After Ash's Bulbasaur intercepts Cacnea's Pin Missile attack with Vine Whip to defend May's, both of them use Vine Whip to send Seviper and Cacnea flying towards Team Rocket while Brock calls the two Bulbasaur as Team Bulbasaur which Team Rocket gets upset for mocking their group's name. They send their Pokémon to attack again, but Pikachu uses Thunderbolt to blasts them off after Brock retrieves all of the Poké Balls they had stolen and the two Bulbasaur does a high five with their vines. Afterwards, Nurse Joy and the kids are thankful to both Ash and May's Bulbasaur to retrieve their Poke Balls until Bulbasaur was transported again by Professir Oak due to Water and Grass-type Pokemon are fighting at his lab. Before being transported back to Professor Oak's lab, Bulbasaur bids farewell to May's Bulbasaur while it happily patted her head with its vines. In The Right Place and the Right Mime, they were used to battle Team Rocket's Pokémon before the former are attacked by Misty's Azurill and Tracey's Marill's Water Gun followed by May's Combusken Fire Spin and Pikachu's Thunderbolt to blast them off. May decides to leave her Bulbasaur with Professor Oak so she can learn from Ash's.
It returns again along with Charizard and Squirtle to battle Brandon at the Battle Pyramid, and battled against Brandon's Dusclops. Although Dusclops managed to bring down Charizard, Bulbasaur was able to endure the unavoidable Shadow Punch and land a hit with Leech Seed, but struggled to overcome the Confuse Ray/Mean Look combo. Ash snapped it out of the confusion and defeated it with Solar Beam. Solrock's Psychic attacks were tougher to overcome, but in the end, both Pokémon were knocked out with a double Solar Beam.
Bulbasaur reappears in An Old Family Blend! in Professor Oak's Laboratory, where Heracross is sucking sap from its bulb, much to Bulbasaur's annoyance. It used Vine Whip to shove Heracross away.
Bulbasaur reappeared in a flashback in The Fires of a Red-Hot Reunion!. It reappeared in The Dream Continues!, where it greeted both Ash and Pikachu while it was with Professor Oak being interviewed by Alexa. It was happy to see Pikachu again. As Ash requested, Bulbasaur happily releases its Solar Beam to get all of Ash's Unova Pokémon's attention in a shining multiple of sparkles. Unfezant, Krookodile, Leavanny, Boldore and Palpitoad finally reunite with Oshawott, Snivy, Scraggy, Pignite and Charizard after they were taken out by Ash.
|Tackle||Bulbasaur and the Hidden Village|
|Vine Whip +||Bulbasaur and the Hidden Village|
|Razor Leaf +||Primeape Goes Bananas|
|Whirlwind -||The Ninja Poké-Showdown|
|Leech Seed +||The Ninja Poké-Showdown|
|Solar Beam +||Bulbasaur's Mysterious Garden|
|Sleep Powder||Misty Meets Her Match|
|Take Down||The Grass Route|
|Dig -||Bulbasaur... the Ambassador!|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.
- Bulbasaur is the first starter Pokémon Ash ever captured.
- Bulbasaur was the first Grass-type Pokémon that Ash has owned.
- Bulbasaur is the second Pokémon Ash owns that chose not to evolve, the first being Pikachu, but he is the first Pokémon that Ash caught that chose not to evolve because Bulbasaur was not ready to evolve yet. Pikachu wants to prove that he can defeat stronger Pokémon without evolving.
- Bulbasaur is possibly the de-facto leader of Ash's Pokémon that are at Prof. Oak's lab.
- Bulbasaur is one of Ash's original six Pokémon, now also counting Charizard (other than Pikachu since Pikachu is always with Ash) that he still has.
- Despite being part Poison-type, Bulbasaur does not know any Poison-type moves.
- Bulbasaur, after Pikachu, is the Pokémon Ash has owned for the longest time period. It is the only member of Ash's original team, besides Pikachu, to remain in his care, and the only one to reside at Oak's lab.