Ash defeated Leon in the Pokémon World Coronation Series final.
The championship battle appears in Pokémon Ultimate Journeys: The Series, where Ash faces Leon, the reigning Monarch and Champion of the Galar region. Ash’s victory made him the officially recognized strongest Pokémon Trainer in the world within the anime’s World Coronation Series storyline.
The result aired during the series’ Japanese run in 2022 and marked the culmination of Ash’s long-running competitive journey. Earlier anime arcs had shown him entering regional leagues, but he did not consistently win those competitions.
Viewers sometimes confuse this achievement with Ash’s earlier Alola League title in Pokémon the Series: Sun & Moon. That was a regional championship; defeating Leon in the Masters Eight tournament established Ash as the World Coronation Series champion.