It is still ongoing with the newest series, Pokémon Journeys: The Series, which premiered in 2019. It features a new storyline with Ash Ketchum and his partner Pikachu traveling the world, competing in the World Coronation Series, and battling new Pokémon.
However, the original anime series, which started in 1997, has ended. It concluded with Ash's victory in the Alola League and his decision to move on from his journey.
Therefore, while the original series has concluded, the Pokémon anime is still running with a new series that is expected to continue for many years to come.