Over the Mountain of Snow! (Japanese: 雪山をこえて！マンムーとユキノオー！！Crossing the Snow Mountains! Mammoo and Yukinooh!!) is the 83rd episode of the XY series, and the 882nd episode of the Pokémon anime. It first aired in Japan on July 30, 2015, in Canada on September 26, 2015, and in the United States on October 3, 2015.
A giant snowy mountain stands between our heroes and their next destination. To cross it, they rent two powerful Mamoswine and climb on board! It’s a treacherous trek up to the summit, but everything proceeds as planned until the Mamoswine make an unexpected turn toward the Frost Cavern, where a mighty Abomasnow blocks the way!
Ash and the others discover that Abomasnow is standing guard over a sick little Snover, and Clemont soon has everyone searching for medicinal plants. With these ingredients, he prepares a remedy, and Snover is soon feeling just fine. After a brief run-in with the Team Rocket trio, our heroes set off once more, and the Mamoswine carry them down the other side of the mountain toward Anistar City!
The episode opens up with Ash and his friends as they rent two Mamoswine to help them get over a snowy mountain. Clemont and Bonnie decide to ride on a Mamoswine together, leaving Ash and Serena to ride a separate Mamoswine up the mountain. However, as they travel up the mountain, the group meets a steep section, which Ash attempts to direct his Mamoswine to climb, only to end up sliding back down. Clemont suggests finding another way around the mountain, but Serena decides to take Mamoswine's reins herself because of the training she got from her mother, a champion Rhyhorn racer. With Serena at the reins, Mamoswine manages to make it up the slope successfully. Ash and Serena's Mamoswine then helps tow Clemont and Bonnie's Mamoswine up using a rope.
Elsewhere, Team Rocket has also followed the group to the snowy mountains, only to regret their decision as they shiver in the cold.
Ash and his friends are then shown slowly crossing a wooden bridge over a gorge. When a gust of wind causes the bridge to sway, the Mamoswine halt their progress. As Ash reassures Serena, the wind stops and the group manages to cross the bridge.
Back with Team Rocket, Meowth spots a cave, and the group runs towards it, hoping to get out of the cold. However, an Abomasnow confronts them at the cave entrance. Jessie sends out Gourgeist to attack with Shadow Ball and Seed Bomb, but Abomasnow deflects the attacks with Ice Punch and Wood Hammer. James sends out Inkay to attack with Psybeam, but Abomasnow blocks it again. Abomasnow then sends Team Rocket flying with an Ice Beam. Abomasnow retreats into the cave, where a sick Snover is revealed to be the reason for its aggression.
Ash and his friends continue traveling the snowy mountain until they notice a large boulder blocking their path. While the group remains worried, the Mamoswine charge and crush the boulders with force, allowing the group to continue along its path. After that, Pikachu and the Mamoswine detect something wrong, and the Mamoswine lead the group down in another direction, to the cave with the sick Snover. Abomasnow begins to attack the group, but Ash, Pikachu and Serena reassure the Abomasnow that they are there to help Snover. Inside the cave, Clemont suggests finding Spring Moss and Mountain Marigolds, which grow around hot springs and in snowy regions, respectively. Ash and Serena decide to try finding Spring Moss inside Frost Cavern, while Clemont and Bonnie decide to search for Mountain Marigolds outside the cave. Pikachu, Chespin, and Braixen are left behind to tend the Snover.
Ash and Serena, trying to find the hot springs, realize that the cave is like a maze and is too large to search. Ash sends out Noibat to use its echolocation and find out which path is the right way to the springs. In the meantime, Clemont and Bonnie also realize that there's too much snow outside for them to search. Clemont then pulls out his invention, the "Snow Flower Finder", which detects a flower beneath them. Bunnelbydigs it out, only to find a Chesto Berry. Clemont then activates his machine at full power to detect more flowers. Inside the cave, Pikachu, Braixen, and Chespin are making balls of snow, which they place on Snover's face to relieve its fever.
Ash and Serena find the Spring Moss with the help of Noibat, while Clemont and Bonnie find the Mountain Marigolds. Bonnie helps retrieving the flowers from high up a cliff. Team Rocket overhears Clemont and Bonnie talking about Snover and decides to take revenge on Abomasnow.
Inside the cave, Clemont mixes a medicine using the Spring Moss and the Mountain Marigolds, which he feeds to Snover. However, Team Rocket interrupts by capturing Abomasnow and trapping the Mamoswine. As Team Rocket sends their Pokémon to battle the heroes, Ash and Pikachu distract Gourgeist while the rest of the group heads off to a higher vantage point to save Abomasnow. Gourgeist uses Shadow Ball, but Pikachu avoids it and strikes back with Electro Ball. James notices the other heroes and orders Inkay to attack them with Psybeam, which the group dodges. Clemont asks Chespin to strike back with Pin Missile, hitting Inkay back. Still not giving up, Jessie tells Gourgeist to use Dark Pulse, but Pikachu dodges and attacks with Iron Tail. Bonnie distracts Inkay with a snowball, and it ends up getting hit by Gourgeist who was thrown back by Pikachu's attack. Clemont then orders Chespin to use Vine Whip in order to throw Braixen to Abomasnow. Braixen uses Scratch to break the net, freeing Abomasnow.
Pikachu and Abomasnow use Thunderbolt and Ice Beam to send Team Rocket blasting off once again. A now healthy Snover then runs out excitedly from the cave to Abomasnow. Later, Ash and his friends say farewell to Abomasnow and Snover. The episode ends with the group reaching the town on the other side where they can finally go warm up.