Ash and his friends arrive in Safari Land, near the Safari Zone, where they come across a Tauros ranch. Wanting to catch one, believing they are now in the Safari Zone, Ash tries to have Pikachu face down the stampede, but Pikachu refuses because he is massively outnumbered. When Ash sends out Charmander, it is immediately pinned by a Growlithe. After a brief trade of Flamethrowers by the two Fire-type Pokémon, Ash and friends are introduced to Lara Laramie, of the Laramie Big P Ranch, who a ranch that preserves and raises wild Pokémon. Brock immediately recognizes the name, as it is said that Pokémon bred by the Laramie clan are of superior standard. After Ash realizes that they are not in the Safari Zone, Lara invites them to the Big P Pokémon Race that will be held the next day. Lara intends to race with her Ponyta, a Pokémon whose mane will burn anyone it does not trust. When Ash tries to touch Ponyta, his hand is burned, and he has Squirtle put out the flames. Lara's main opposition is Dario, a Dodrio Trainer. Lara explains that the winning team of Pokémon and Trainer will be named as an honorary member of the Laramie clan.
At the festival in Laramie Village, while many are cheering Lara on, Dario arrives to tell Lara that her Tauros have suddenly begun attacking each other over a bout of confusion. After they arrive on the scene, Lara tells Growlithe to tame the Tauros, but during all this Ponyta is spooked, causing Lara to be thrown off, injuring her arm. As Ash tries to rein in Ponyta, it is revealed that Team Rocket spooked the Tauros that led to Lara's incapacitated state, at the request of Dario. Dario intends to win the competition by any means necessary, while Team Rocket seeks to make money from the Laramie fortune.
Back at the Laramie household, with her injured arm, Lara would not be able to ride Ponyta, but after seeing Ash try to rein in Ponyta, she tries to convince Ash to take her place. At first, Ponyta is reluctant and burns Ash again, but Lara insists that both stand to gain from winning, with Ash improving his Trainer skills and Ponyta from its upbringing. Ash and Ponyta use the entire night to prepare for the race.
At the race, many pairs have entered the race, among them Dario and Dodrio, Ash and Ponyta, Brock and Onix, Misty and Starmie, as well as the all-Pokémon team of Pikachu and Squirtle representing Ash's entry. When the race starts, Dario and Dodrio quickly take the lead, while Pikachu and Squirtle quickly fall to the back of the pack , though they do eventually catch up. At the same time, Team Rocket make two well-aimed slingshots that spook a Tauros, and he runs into a Nidorina, and they take their frustrations out on each other. After a sprint comes a steep uphill portion, where Pikachu is forced to push Squirtle up the hill, putting them far behind once again. Then, the racers come upon a downhill section where another violent accident occurs: an Electrode and its Trainer roll down the hill uncontrollably, and a pitfall trap dug up by Team Rocket manages to take it out. This gives Dario a significant lead, while Electrode's Explosion attack manages to incapacitate a Sandslash, Raticate, but most importantly Ash and Ponyta. Ash and Ponyta, however, are able to continue, thanks to Pikachu's Thunder Shock and the fact that the other two Pokémon were still lagging far behind.
Farther up ahead is a stepping-stone portion, which Dario and Dodrio cross with ease. However, another two chasers are forced out of the competition, with Brock's Onix being fearful of water and a farmhand with his Rhyhorn attempting to cross a stone that sank. This leaves only four teams still racing. While Ash and Ponyta navigate the stones, Starmie and Squirtle swim across the water easily. At the next portion, teams must make a stop and allow their Pokémon to eat an entire plate of Pokémon food before sprinting to the finish. Dario and Dodrio are the first to arrive, but the other racers catch up whilst Dodrio's three heads fight over who gets to eat first.
Desperate to eliminate the other three teams, Dario is forced to use Team Rocket's assistance once more; from which Ash and Misty learn of Dario's alliance with Team Rocket. Ash tells Pikachu and Squirtle, who had both been scarfing down Pokémon food during Team Rocket's motto, to take care of Team Rocket, but Arbok's Glare paralyzes them, while Starmie is blinded by Weezing's Sludge. This allows Dario enough time to take off towards the finish. Misty decides to handle Team Rocket and implores Ash and Ponyta to keep going. Team Rocket causes Ponyta to literally get fired up, shocking Arbok. Weezing tries to attack Ponyta despite James telling it not to use gas, but Ponyta's flames ignite Weezing's Smog, and it explodes, sending Team Rocket flying.
Now desperate to make up ground, Ash and Ponyta race towards the finish line. When Ash and Ponyta catch up, Dario then orders one of Dodrio's heads to Peck Ponyta, slowing it down. Dario then speeds off, taking the lead, Everyone is then startled when Ponyta evolves through sheer will to win into the much-faster Rapidash. Ash and Rapidash catch up to Dario and by a nostril manage to overtake him to claim the victory in a photo finish. Believing that he had been cheated, Dario orders Dodrio to attack Rapidash, but is sent flying by a kick from its powerful hooves. Lara proudly holds the winner's flag and Rapidash nuzzles Ash.
As the festivities wrap up, Ash and his friends bid farewell to the Laramie Ranch, and continue on their way to the Safari Zone. Meanwhile, Dario, who blames Team Rocket for his loss, has tied them to a tree to scold them. His Dodrio delivers its own revenge, pecking the trio mercilessly after Meowth insults it.