1x129 - Pokémon Horizons

Roy and the others visit the Dragon Shrine to meet with the Black Rayquaza. After Roy manages to get through to it, Pagogo helps it Dragon Terastallize! A battle for the purpose of testing Roy and Uruto's strength then begins; And this time, it's for the sake of becoming its true Partner... The Time Has Come for the Showdown with the Black Rayquaza?!