Ash and Goomy are training in the Lumiose Badlands when an injured Spoink appears and leads Ash and the others to its oasis home. There, our heroes find a group of Spoink under the control of an unpleasant Grumpig, who’s using its psychic powers to control them and steal all their food!
When our heroes retreat to plan their strategy, they become trapped in a cage set by Team Rocket! It turns out Grumpig is in cahoots with the villains to seize the oasis and its impressive food supply from the resident Spoink. First, Goomy slips through the bars and challenges Grumpig. Then, when Ash frees himself and leaps into the battle, Goomy evolves into Sliggoo to protect him!
When Grumpig realizes Jessie, James, and Meowth were just using it for their own selfish ends, it angrily sends them blasting off, and then apologizes to the Spoink with a gift of food. All is forgiven, and our heroes are off once more to Lumiose City!