Platinum's Rapidash was first seen as a Ponyta in Stagestruck Starly where he was used as Platinum's steed. He was mainly used as her mode of transportation, not seen in many battles, until A Conk on Cranidos's Cranium where he was used in Platinum's first Gym battle against Roark. The battle ended quickly, however, as he was quickly defeated by a combination of Double-Edge and Slam that sent him flying into a wall and was knocked out as a result. In Ring Around the Roserade II he was used in Platinum’s Gym battle against Gardenia, but like his previous Gym battle, he was defeated in only a few seconds by Roserade's Poison Jab.
From that point on he was used considerably less than usual, being used mainly for transportation or Gym training until Brash Bronzong I where he was used to battle Byron. In what can be considered his crowning achievement, he defeated both of Byron's Bronzong in one shot, ending his horrible losing streak at the same time. In Hurrah for Rapidash after refusing her father's plea to not do anything dangerous, Ponyta evolved into a Rapidash and left with her after the three decided to split up and protect the Lake guardians and the Sinnoh Region.
In To and Fro Froslass Rapidash was used in Platinum’s Gym battle against Candice where he battled against her Froslass. During the battle Platinum boasted about the speed he gained with his evolution into a Rapidash, but Candice had Froslass use Wake-Up Slap that became more powerful due to him using Rest a few moments prior to its usage. Rapidash was recalled and switched with Lopunny afterwards, but he returned after Lopunny used Healing Wish to sacrifice herself to revive Rapidash who defeated Froslass and gave Platinum her seventh Gym Badge.
He was used in the battle against Jupiter but after a long battle, he was defeated along with the rest of Platinum, Candice, and Maylene's Pokémon and was used to keep them warm while they were trapped in the blizzard until they were rescued.
Rapidash is used in Platinum's battle against Castle Valet Darach where, like his days as a Ponyta, was quickly defeated by a single Feint from his Gallade.
