As the twentieth film in the series, Pokemon: I Choose You! returns to origins of the Pokemon series when Ash first met Pikachu!

When Ash Ketchum oversleeps on his 10th birthday, he ends up with a stubborn Pikachu instead of the first partner Poke´mon he wanted! But after a rocky start, Ash and Pikachu become close friends and true partners—and when they catch a rare glimpse of the Legendary Poke´mon Ho-Oh in flight, they make plans to seek it out together.

Trainers Verity and Sorrel join Ash on his journey, and along the way, they meet the mysterious Mythical Poke´mon Marshadow. When they near their goal, an arrogant Trainer named Cross stands in their way. Can Ash and Pikachu defeat him and reach Ho-Oh as they promised, or will their journey end here?