Elisa is a character of the day who appeared in Beg, Burrow and Steal.

Elisa is a Pokémon Ranger who works and lives on Izabe Island. A lifelong friend of Hal's, Elisa always doubted her friend's story about a secret Pokémon paradise known as the Trapinch underground labyrinth that he had seen when he was much younger.

However, after following a Trapinch with a tracking device on it, Elisa discovered, along with Ash and his friends that Hal was indeed telling the truth. Once she saw the paradise, Elisa apologized to Hal, and both promised that they would keep the paradise safe from the likes of Team Rocket for years to come.

(Source: Bulbapedia)