S21

Pokémon the Series: Sun & Moon—Ultra Adventures is the twenty-first season of the dubbed version of the Pokémon anime. It is the second season of the. The season follows and  as he continues his, attending the Pokémon School in the Alola region.

In, it premiered on on March 24, 2018 with the dub premiere of A Dream Encounter!, and concluded on February 23, 2019 with Turning the Other Mask!. It originally aired in the United States as part of the 2018-2019 Disney XD Saturday morning line-up, with the exception of seven episodes that aired as part of their summer 2018 Monday evening line-up. In New Zealand, it debuted on March 1, 2018 on 's video-on-demand service. In, it debuted on March 10, 2018 on Teletoon. This season skips SM064, which was banned from airing, making it the first undubbed non-clip show episode of the main series since EP250 in the original series.

It is preceded by Pokémon the Series: Sun & Moon and succeeded by Pokémon the Series: Sun & Moon—Ultra Legends.

Blurb
''When Ash sees the Legendary Pokémon Solgaleo and Lunala in a dream, he makes a promise to them. But when he wakes up, he can’t remember what it was! Will the strange Pokémon called Nebby help jog his memory? Along with their new friend and the rest of the students at the Pokémon School, Ash and Pikachu explore the Aether Foundation, an organization dedicated to Pokémon conservation and care. But it may not be as innocent as it seems, and Ash and his friends will have to work together to protect the people and Pokémon they care about as they face a mysterious power like nothing they have ever seen.''

Important events

 * finds and befriends a, which nicknames Nebby. (SM044)
 * Ash learns about the Aether Foundation and Ultra Beasts upon meeting Lusamine, Professor Burnet, Faba, and Wicke for the first time. (SM044)
 * Ash learns that 's fear of touching Pokémon is related to . (SM047)
 * becomes unable to touch any Pokémon again after encountering Gladion's Silvally. (SM048)
 * 's breaks free of its mask, revealing its . (SM049)
 * Lillie remembers the incident that made her afraid of touching and overcomes her fear, becoming able to touch all Pokémon once again. (SM049)
 * Faba kidnaps Nebby, which then evolves into . (SM050)
 * Faba summons a, which takes Lusamine through an Ultra Wormhole. (SM050)
 * changes her outfit into her "Z-Powered form". (SM051)
 * and travel to Poni Island with, following Lillie and Gladion who are searching for a way to save Lusamine. (SM051 - SM054)
 * Ash obtains a Solganium Z, and the guardian deities upgrade Ash's Z-Ring into a Z-Power Ring. (SM052)
 * Ash, his classmates, and Gladion enter an Ultra Wormhole with Nebby, having evolved into, in search of Lusamine. (SM052 - SM054)
 * Ash, his classmates, and Gladion find Lusamine in Ultra Deep Sea, only to discover she has fused with Nihilego. (SM053)
 * Ash's Electrium Z temporarily changes into a Pikashunium Z allowing Ash and Pikachu perform . (SM054)
 * Ash and Pikachu defeat Lusamine and free her from Nihilego's control, and return to their own world. (SM054)
 * Nebby is revealed to have returned to the . (SM055)
 * Professor Kukui proposes to Professor Burnet and get married. (SM055)
 * Lusamine, Wicke, and Faba invite Ash and his classmates to join the "Ultra Guardians" task force to deal with any future Ultra Beast incidents, which they accept. (SM055)
 * Ash visits Ula'ula Island for the first time. (SM060)
 * Ash and his classmates go on their first Ultra Guardians mission, catching a and releasing it back into Ultra Space. (SM061)
 * An joins Team Rocket and travels to the  in Kanto, where it is appointed as Matori's assistant. (SM062)
 * Ash, the Masked Royal,, and participate in a Battle Royal and the Masked Royal wins. (SM063)
 * Ash and his classmates go on their second Ultra Guardians mission, freeing a and allowing it to fly back home. (SM069)
 * Team Rocket receives a Z-Power Ring from Nanu, while Jessie receives a Mimikium Z from Acerola's Mimikins. (SM073)
 * Professor Kukui is revealed to have told Ash and his classmates about the Pokémon League he's establishing in Alola. (SM074)
 * and go on their third Ultra Guardians mission, catching a  and a, and releasing them back into Ultra Space. (SM078)
 * receives an Icium Z from the newly evolved Alolan . (SM080)
 * Lillie offers an Ice Stone to Snowy, but it refuses to evolve for the time being. (SM080)
 * and go on their fourth Ultra Guardians mission, catching a  and releasing it back into Ultra Space. (SM085)
 * A small Ultra Wormhole opens above the Altar of the Sunne, covering Alola with dark clouds and draining the region of its Ultra Aura, causing all adults to lose their energy and motivation, and draining Z-Moves of their power. (SM087)
 * is revealed to have joined the Ultra Guardians and acquired a Z-Power Ring. (SM087)
 * A special Team Rocket unit led by Matori called the "Matori Matrix", arrives in Alola on 's orders, but fails in its attempts to capture Necrozma, Nebby, and Lunala, and is forced to retreat. (SM087 - SM090)
 * Ash and go on their fifth Ultra Guardians mission, traveling to the Altar of the Sunne and to 's home world through an Ultra Wormhole. (SM087 - SM090)
 * Necrozma brings the light back to 's home world, restoring it to its former state, and the Ultra Guardians, Nebby, and Lunala return to Alola. (SM090)

Additions

 * Ash's Poipole (SM067)

Evolutions
The following Pokémon evolve:
 * Ash's →  (SM063)
 * Mallow's →  (SM082)

Releases
The following Pokémon are released:
 * Ash's Poipole (SM090)

Trials

 * Thrifty Megamart trial (SM076)
 * 🇮🇸 grand trial (SM077)

Trivia

 * This is the first season whose trailer is dubbed to and.