Synopsis

Having asserted herself against Tapu Fini, Hapu has at last earned the title of Island Kahuna of Poni Island, and she challenges Ash to her Grand Trial. The trial demands that Ash face her in battle using a single Pokémon. With Hapu's Muddy Water proving a formidable obstacle, Ash and Pikachu find themselves in a difficult contest. Can they triumph in the Grand Trial and complete Ash’s research?