Harley's Banette was obtained shortly before the Battle Frontier.
Banette debuted during the Hoenn Grand Festival when Harley used it to impress, and disturb, the judges by having it use Thunder on itself. When it was hit by the powerful attack, Banette simply cackled as though the electricity wasn't hurting it at all. It was also used in the double battle against May alongside Cacturne but May's Bulbasaur and Beautifly managed to win the battle.
Bannette reappeared in Kanto when Harley lent his Banette to Jessie in an attempt to help her beat May in the final Pokémon Contest before the Grand Festival in an attempt to prevent May from entering. Because it was unfamiliar with her, Jessie continued to tell Banette to use Frustration. This eventually resulted in Jessie's loss to May. Harley also used Banette in the appeals round during the Kanto Grand Festival.