Hilda is a girl who lives in Nuvema Town, along with her childhood friends Cheren and Bianca. If chosen as the player, she will receive a starter Pokémon and a Pokédex from Professor Juniper. After setting off on her Pokémon journey at the same time as Cheren and Bianca, Hilda will at some point be asked by Fennel to do some sort of quest; in return for its completion, Hilda will receive a C-Gear.

As well as encountering and battling her childhood friends at various points during her journey, Hilda will also meet a young man known as N, who wishes to create separate worlds for humans and Pokémon. In order to achieve his goals, he and Hilda will battle several times during the course of the game. Hilda will also battle Team Plasma at various stages of her journey. At the game's climax, Hilda is recognized as a hero by Reshiram or Zekrom, depending on the version.