Pokémon Go is the first ending theme for the English dub of the Pokémon anime but it was also used as the opening for the The Mastermind of Mirage Pokémon 10th Anniversary opening.
The opening begins with the "Pokémon The Mastermind of Mirage Pokémon A 10th Anniversary Special" logo appearing on screen. Mewtwo is the first scene after the logo and it attacks Mew with its tail knocking it to the ground and then uppercuts it.
Ash, Professor Oak and the rest of the gang are then seen outside the castle confronting Dr. Yung who has an Entei, Articuno and Zapdos protecting him. Ash commands Pikachu to use Iron Tail.
May throws a Poké ball and the next scene transitions to Misty's Gyarados and May's Combusken attacking the mirage Articuno and Zapdos but they both get hit.
Aggron creating a sand whirl is shown and then Staryu avoiding the sand spiral right after. Professor Oak throws his Poké ball and Dragonite is released. Mewtwo uses a Shadow Ball against Dragonite and it fly's up into the sky but Mewtwo fly's up as well and begins punching Dragonite.
Ash and his friends look on as they tend to their Pokémon's injuries. Mewtwo, Entei, Articuno, Zapdos and Dr. Yung are shown right after.
The opening ends with Pikachu using Volt Tackle and the "Pokémon The Mastermind of Mirage Pokémon A 10th Anniversary Special" logo appears again.