Ash and his friends meet Cynthia, the Champion of the Sinnoh region. Apparently, Cynthia plans to enter a tournament taking place in Lacunosa Town. Hearing that the winner of the tournament gets to battle Alder, the Champion of the Unova region, Ash and his friends...
After they hear that not only will they get to watch Cynthia battle firsthand, but if they win the tournament they will get to battle Alder, the Champion of the Unova region, Ash and his friends decide to participate. Together with Cynthia, they set off towards Undella Town with Cynthia's truck. On the way, the extremely rare Meloetta suddenly appears right before them. Cynthia stops but then Meloetta suddenly collapses from heavy injuries.
Ash then recognises it as the Pokémon he saved in An Epic Defense Force! and Cynthia identifies it. The gang lay it down and Cynthia sprays Meloetta with a Super Potion. She then has Iris and Cilan get an Oran Berry while Ash and Cynthia go get some ice.
Ash and Cynthia come to a lake and Cynthia calls her Glaceon. She has Glaceon use Ice Beam at the lake to freeze it. She recalls Glaceon and they collect the ice.
They return to Meloetta and Pikachu and Ash puts the ice on Meloetta's head. Cynthia then gets a phone call and is asked to leave, so Ash and Pikachu are alone. Ash's Oshawott suddenly comes out of his Poké Ball and then develops a crush on Meloetta. Ash then sees the ice has melted, so he has Oshawott to look after Meloetta while he go get some more ice.
Meanwhile, Iris and Cilan found some Oran Berries on a top of a mountain and Iris relaized that the rock is too broken to climb. She called her Emolga to get the Oran Berries and they head back. They then find Ash and Pikachu working to on the ice, so Iris sends Emolga to get the Oran Berry to Meloetta.
Emolga then finds Oshawott flirting with Meloetta and flies over when a gust of wind blows her into Oshawott's head and the Oran Berries gets near Meloetta. Meloetta found the Oran Berry and flies off. When the gang went back, Oshawott and Emolga starts fighting when Meloetta sings which calms them down. Cynthia then arrives and explains Meloetta's song and without it, no one can be calm. Meloetta then leaves. Soon after, Iris challenges Cynthia to a battle and she accepts.
Meanwhile, Team Rocket searches for Meloetta. Meowth found Meloetta and they run after it.
Cynthia will use Garchomp and Iris will use Axew. Iris starts the battle with Scratch and then uses Dragon Rage but neither is successful. Cynthia then has Garchomp use Dragon Rush and then Draco Meteor, both which had an effect. However, Axew refuses to give up and immediately learns Giga Impact, charging to Garchomp and doing some damage. Garchomp then uses Brick Break while Axew is recharghing, and then has him stop. The battle is then called off by Cynthia.
Team Rocket searches for Meloetta at the airport when Ash, Iris, Cilan, and Cynthia came over to the dock and Meowth realized Meloetta is following them. They contact Dr. Zager and follows the gang. Cynthia then tells Ash that he has an old friend waiting for him in Undella Town.