This article is about an episode of the Pokémon animated series that has not been dubbed into English. As such, its coverage may contain romanized Japanese names, rather than dub names.
(Japanese: 修行開始！テラリウムドームTraining Begins! Terarium Dome) is the 116th episode of Pokémon Horizons: The Series, and the 1,348th episode of the Pokémon animated series. It first aired in Japan on November 7, 2025.
In the morning, the Rising Volt Tacklers discuss their plans at Blueberry Academy not only among themselves but also with their friends. Afterwards, they meet Briar and her assistant, Carmine, who they had momentarily forgotten from the last time they met in Kitakami. They explain the situation with the Strong Spheres and she agrees to look further into it, excited with another aspect of Terapagos she has yet to discover. In the meantime, Lacey helps to train the Rising Volt Tacklers by recommending some Pokémon they could battle and spots in each of the four areas in the Terarium. Liko, Roy, and Dot head off to the areas they decide to train in while Lacey tracks down Drayton and Ult, who ran off while she was explaining the training plan. In the Savanna Biome, Liko has Meowscarada and Charcadet battle a wildPyroar before being joined by Ann. In the Coastal Biome, Dot has Tinkaton battle a Crabrawler, while Ult runs away from Lacey after she gives him some advice when he gets attacked by a sleeping Overqwil in the Polar Biome. In the Canyon Biome, Roy trains his Pokémon, not noticing Drayton watching him from elsewhere.
After Kilowattrel saves Crocalor from falling off a bridge, Drayton appears and compliments their teamwork while wondering what Roy is up to. Roy asks the Elite Four member to train him and Drayton opts to do so via his Rotom Phone. While collecting berries according to Drayton's instructions, Lacey appears and becomes infuriated when she finds out what her fellow Elite Four member put Roy through. Lacey confronts Drayton in the League Club Room for using Roy to complete his Blueberry Quests under the pretense of training. Director Cyrano appears in the room and mentions Director Clavell asking him to look after Roy and the others during their stay. The director even mentions the time when Roy battled againstHassel in an event, which piques Drayton's interest since his grandfather is friends with the art teacher, resulting in him bringing Roy somewhere. Meanwhile, Ult traverses through the Chargestone Cavern and comes across a Galvantula. He decides to have Sableye battle it, ignoring Lacey's advice and winds up getting the Darkness Pokémon trapped in the EleSpider Pokémon's webs. Lacey arrives to find Sableye just beating Galvantula and notices Ult not heeding her advice based on the presence of the eletric webs on Sableye, leading to him running away again. As Dot meets Penny again thanks to Gimmighoul, Carmine informs Liko of Briar's request to meet her in the lab with Dot and Pagogo. She also reveals she knows about the visitors being part of the Rising Volt Tacklers from her teacher and encourages Liko to continue on regardless of what others think.
Drayton brings Roy to the Polar Plaza and the latter asks for a Double Battle. The Blueberry Academy student calls out Archaludon and Kingdra to battle against Crocalor and Kilowattrel, and he begins the battle by having the Dragon Pokémon use Hurricane while the Alloy Pokémon charges up. While unable to get close, Kilowattrel's wings are charged with electricity, resulting in Roy calling for it to use Electro Ball on Archaludon. The attack is negated by Archaludon using Electro Shot, but Kingdra is hit by a supereffectiveDisarming Voice before the Alloy Pokémon uses Snarl to cancel the other sound-based move. Roy is forced to have Crocalor ride on Kilowattrel, and Drayton has Kingdra use Hydro Pump that the Frigatebird Pokémon is able to outmaneuver. Crocalor attacks with Flamethrower, only for Draco Meteor to force the two Pokémon to focus on avoiding the meteors, which prove to be even more difficult when Kingdra's Hurricane sends the meteors in unpredictable directions. Using Disarming Voice and Uproar, the meteors are pushed away from them. Drayton decides he needs to build up momentum and has Kingdra use Rain Dance, which not only increases its speed thanks to Swift Swim, but also increases power to its Water-type attacks. Drayton has Archaludon use Electro Shot, which fires immediately due to the rain catching Roy off-guard. This defeats Kilowattrel and renders Crocalor as the only Pokémon capable to battle. His attempt to use Stomping Tantrum fails due to the slippery surface and Kingdra seizes the chance to defeat the Fire Croc Pokémon with a powered-up Wave Crash, making Drayton the winner. Roy is desperate to grow stronger but is left confused when Drayton tells him to relax instead. In the Coastal Biome, Lacey catches up to Ult again and declares they shall study to help the latter become stronger.
