S22E17 : A Grand Debut!

Following her standing up to Tapu Fini, Hapu has finally become the Island Kahuna of Poni Island, and Ash challenges her to her Grand Trial. Her trial requires Ash to battle her with just one Pokémon. With Hapu using her Mudsale, Ash and Pikachi face a tough battle. Will they be able to win the Grand Trial and finish Ash's research project?