Bulbasaur... the Ambassador! (Japanese: さよならフシギダネ！オーキドていのぼうけん！！ Goodbye Bulbasaur! Professor Oak Residence's Venture!!) is the 16th episode of Pokémon: Master Quest.
After winning the Mineral Badge from Jasmine, Ash and co. decide to head to the next Gym, located at Mahogany Town. To get there, they have to go through Ecruteak City again. Sometime later, Ash calls Professor Oak and is surprised to see his mom at the lab. Professor Oak and Tracey then come in and explain the situation: A few days ago some Hoppip, Skiploom and Jumpluff landed in an area occupied by some Oddish, Gloom, Vileplume and Bellossom and begin to fight over it. Then some Water Pokémon join in the dispute. To solve the problem, Professor Oak requests Ash send in Bulbasaur to straighten things out. What kind of solution will Bulbasaur come up with?
As the heroes continue their journey, they start running back, seeing some milk canisters are being rolled to them. A man asks for their help, so the heroes stop the canisters from being rolled. The man thanks them for assistance and decides to give them a ride to Ecruteak City, since they need to go back there. The man, Carter, drove them to the blimp, which will take them to Ecruteak City in no time, pleasing the heroes. As the Pokémon eat, Ash contacts Oak, but Mimey appears on the screen. Ash's mom comes, greeting her son. Ash asks her what is she doing in Oak's lab, so she responds there has been some trouble. Tracey and Oak greet Ash, the latter telling about the problem. As the wild Pokémon roam in the garden near the lab, this caused a feud between two groups of Pokémon. Suddenly, Bulbasaur approaches Ash to hear the problem.
As a group of Hoppip, Skiploom and Jumpluff were spreading pollen, they got into a feud with Oddish, Vileplume, Bellossom and Gloom. The Water Pokémon near the lake worried about their home, so entered the feud as well. Since they couldn't solve the problem, Oak asks of Ash to send Bulbasaur to the lab, since it knows how to deal with these problems. Bulbasaur is up to the challenge and gets sent to the lab. Oak, Delia and Tracey have confidence in Bulbasaur to resolve the problem. The heroes go aboard the blimp. Team Rocket spot them and sneak into the plane. Despite the heat in the room, Meowth found a cold storage area and go inside it. However, the door locks behind them. Meanwhile, Bulbasaur gets visited by Ash's Heracross, so Bulbasaur uses Vine Whip to keep it at bay from drinking its sap.
Bulbasaur attempts to persuade them, but fails. Bulbasaur tries to bring some Pokémon together, but gets slapped instead. Bulbasaur tries to merge all three groups, but gets attacked instead. Bulbasaur is angry and uses Vine Whip on them, so these groups go after Bulbasaur. Seeing the situation, Tracey sends Marill, Scyther and Venonat to help, even Heracross joins in the fight. Bulbasaur absorbs energy and fires a Solarbeam in the sky, stopping the attacks and calming the Pokémon down. The Grass Pokémon become friends and dance for this friendship. Tracey records this and makes a sketch. Oak is impressed by this event. However, the Water Pokémon disagree with the Grass Pokémon. Oak sees they might have to make a new lake to prevent disagreements between these two groups. Bulbasaur sighs at this event. Team Rocket, meanwhile, are too cold, so Jessie goes to open the door. However, the door is locked, so Team Rocket yells for help.
At the end of the flight, the heroes thank Carter and walk away. Team Rocket manages to bash the door, but are frozen. When the blimp takes off, Team Rocket falls out of the blimp. Ash contacts Oak and is told Bulbasaur needs to stay longer at the lab. Oak tells of Bulbasaur's success, but also tells that the Grass Pokémon are arguing with Water Pokémon, so asks of Ash to let Bulbasaur stay until the new lake is made. Ash understands and lets Bulbasaur stay, being proud of it. Next day, Tracey's Marill searches and finds a spot for the new lake. Bulbasaur yells, summoning the Grass Pokémon to the place. Bulbasaur uses Razor Leaf on the grass, then digs out a portion of the land, presenting the Grass Pokémon they need to dig. After some time, Bulbasaur digs out and sees a rock it cannot dig out. It runs away to the Water Pokémon and persuades Poliwhirl to help making the lake. Next, Bulbasaur negotiates with Sandslash, who also help.
Tracey is confused for the Pokémon are summoned here, even his Marill joins with Poliwhirl, who use Water Gun. Oak believes they are trying to soften the rock, enough for Sandslash to dig through. The Pokémon dig out, while Delia and Mimey come with the lunch for the Pokémon. After more digging, a giant rock stands at the bottom. Bulbasaur uses Vine Whip to pull, while the other Pokémon help it to pull it out. Tracey thinks they should help, but Oak and Delia disagree, as the Pokémon can solve this, since now they help instead of arguing. With a lot of effort, Bulbasaur and the Pokémon pull out the giant rock. Sandslash dig out and suddenly run away. Tracey and Oak notice water at the bottom. The Pokémon cheer, but an Oddish falls down. The giant rock falls down, so Bulbasaur pushes Oddish away, but the rock is falling on Bulbasaur.
Bulbasaur remembers its memories with Ash: the first encounter with Ash when it was captured, the battle in the Indigo Plateau, the time he was to evolve in front of the Venusaur with the Ivsaur, the day it met Gloom and was charmed by it and the days spent on the Orange Islands. In Johto, Ash wakes up and finds Misty and Brock asleep. He looks up to the sky and mutters "Bulbasaur". Oak, Tracey and the Pokémon push away the rock, but do not see Bulbasaur. However, Bulbasaur emerges from the dirt, so Oak sees it dug itself to prevent damage. Bulbasaur shakes off the dirt, then is hailed as a hero among the Pokémon. Tracey remembers Bulbasaur can't use Dig, but Oak sees at times one can use skill it did not know it possessed.
The heroes view the video Tracey made and are impressed by Bulbasaur. Oak and Tracey report success, but as soon as Bulbasaur left, the Grass Pokémon argued again until Bulbasaur stepped in once more. Oak asks of Ash to have Bulbasaur stay at the lab longer. Ash is sad to hear Bulbasaur won't be able to be with him, so asks Bulbasaur what it thinks. Ash sees Bulbasaur wants to stay, so Ash lets it go, ordering Prof. Oak to take care of it. As the heroes go out of the Pokémon Center, Bulbasaur sees a Hoppip and a Gloom fighting over an apple. Bulbasaur splits the apple and gives it to them, then looks up to the sky.
- With Bulbasaur staying at Oak's lab, Pikachu is the only Pokémon that remains on Ash's Team throughout this and every other Pokémon series.
- The "Who's that Pokémon?" is Arbok.