Ash and his friends are on their way up a hill when a couple of milk cans start to roll towards them. They break into a sprint until someone calls out to them, and soon they stop the runaway cans. The group helps load them back into the man's vehicle. He asks where they are headed, and upon hearing that they are going to Ecruteak City he offers to drive them part of the way.
They arrive at an airport, and their escort, Carter, says it will get them to the Moomoo Ranch near Ecruteak City. While they wait for their tickets, Ash calls Professor Oak's Laboratory. On the other side, however, are Mimey and Delia. Tracey and Professor Oak then appear onscreen. Oak explains that the many wild Pokémon that live in his lab’s sprawling gardens have recently had trouble. A group of migrating Hoppip, Skiploom and Jumpluff decided to stop at Oak’s gardens, but this ignited a territorial squabble with the resident Oddish line and then the Water-type Pokémon. Oak asks Ash if he could send over his Bulbasaur to act as the peacemaker, given its history with Melanie. Bulbasaur happily accepts the task, so Ash transfers it directly to the Professor. The call ends, and Oak greets Bulbasaur as it arrives.
Carter and the group enter the waiting blimp, and Team Rocket decide to sneak aboard as well. The trio enters through the cargo hold but finds it to be a little stuffy. Meowth points out a mysterious door, and it turns out to be a freezer room. The trio happily enters, seeking refuge from the heat, though the door latches shut behind them and effectively traps them in.
Tracey, Oak, and Bulbasaur set off to the lake. Along the way, Heracross flies in and makes a beeline for Bulbasaur's bulb. He begins suckling for nectar, resulting in Bulbasaur Vine Whipping Heracross. After arriving, Bulbasaur rushes into the three-way conflict and tries to negotiate with each of the parties. However, its negotiation attempts fail, as the three fronts turn on Bulbasaur and go on to attack it. Tracey sends his three Pokémon to end the fight, and Heracross enters as well. Though the fight ends when Bulbasaur releases a blinding Solar Beam straight into the sky. Stunned, all the Grass Pokémon learn to respect Bulbasaur and each other. They exchange a "peace dance" to commemorate their new truce, and Tracey films the entire exchange. However, the Water-types are still feeling uneasy towards the Grass Pokémon.
The group's blimp arrives at Moomoo Ranch. Carter bids Ash and his friends a farewell as he drives off. Soon, Team Rocket break open the blimp’s fridge door but emerges frozen. As the blimp takes off again, the Rocket trio slides out of a hatch door and plummets towards the ground. Later, Oak updates Ash that he will need Bulbasaur for a while longer as the Water Pokémon continue to fight with the Grass-types. Tracey adds that a new grass field will be constructed, but this will take some time to complete. Ash agrees to leave Bulbasaur at the lab, thanking the Seed Pokémon for helping the Professor out.
The Professor, Tracey, and Bulbasaur venture out into the field once again. Tracey calls on his Marill's assistance, and it soon finds a potential underground spring. Bulbasaur calls out, and its booming cry summons all of the Grass-types over. Bulbasaur announces to them that this site will be their new home. It promptly sends out a Razor Leaf to cut an outline of the new lake and uses its vines to dig it out. The Grass Pokémon begin to dig into the ground. Bulbasaur soon hits a tough rock layer. It isn’t giving up though, and it runs off to gather the perfect team; a group of Poliwhirl and Sandslash. The choice puzzles the Professor and Tracey. They watch in amazement as the Poliwhirl soften the bedrock with their Water Gun attacks, while the Sandslash Dig into the ground. Delia and Mimey later arrive to deliver lunch for the hardworking Pokémon. Work soon grinds to a halt after one of the Sandslash uncovers a giant boulder wedged into the ground. Bulbasaur lassos its vines around the obstacle and the other Pokémon help it to pull the rock out of the way. Tracey considers helping the Pokémon out, but Oak and Delia remind him that the project has brought all of the once warring Pokémon to collaborate. The boulder eventually gives way allowing Bulbasaur and the others to finally heave it out. The Sandslash suddenly rush out of the pit before the underground water begins to fill it. As the Pokémon cheer, the ground collapses underneath an Oddish and the giant boulder. Bulbasaur jumps into action and manages to throw Oddish to safety.
Instead, Bulbasaur finds itself in the rolling boulder's path. Time appears to slow down and everyone watches the unfolding scene in horror. An almighty smash sound is heard, and Bulbasaur reflects on its life. Ash awakens from a daytime nap and looks into the sky to see a cloud that reminds him of his Bulbasaur. Meanwhile, Oak and Tracey manage to push the rock into the growing lake. They scour the area, but Bulbasaur is nowhere to be seen. Oak calls out. Everyone gasps when Bulbasaur emerges from the dirt, seemingly unscathed. It jumps up the escarpment and shakes itself clean of the muck. The Grass-types are thrilled to have their hero and throw Bulbasaur into the air several times as a show of gratitude. Tracey marvels that Bulbasaur cannot usually learn the move Dig, but Oak notes that in times of need, it is possible to call upon power never known to it previously.
Oak calls Ash and his friends again for another update. Ash is glad to see that Bulbasaur helped restore the peace back at the lab. The Professor then asks Ash for another favor; for Bulbasaur to remain at the lab a while longer. Ash is initially sad, but Bulbasaur offers him some reassurances. With that, the decision is made that Bulbasaur will remain at Professor Oak's lab. Ash wishes Bulbasaur good luck with its new responsibilities before continuing on his journey through Johto. Bulbasaur soon begins its new duties in Kanto. After breaking up a squabble between a Gloom and a Skiploom over an apple, Bulbasaur looks up to the sky, thinking of Ash and knowing he'll be just fine.