The player can use the Zygarde Cells and Cores that they collect in the Zygarde Cube with a Reassembly Machine on Route 16 on Ula'ula Island to create different Zygarde forms. The player can create multiple Zygarde if they have the right amounts of Zygarde Cells and Cores.
The Reassembly Unit will always use the maximum amount of Cells and Cores it can in assembly operations.
If Zygarde is assembled completely from Cells and Cores from the Zygarde Cube, its level depends on whether the player has become the Champion. Before the player has become Champion, assembled Zygarde will be level 30, but after, they will be level 50.
After becoming Champion, the player and Lillie visit Tapu Koko's shrine at the Ruins of Conflict to thank it. Tapu Koko will then challenge the player, acting as the final battle the player has before the credits roll. If Tapu Koko is defeated without capturing it or fled from, it will respawn after the player successfully defends their title.
After the credits, the player can challenge the other three guardian deities.
After becoming Champion, if the player visits the Route 8 motel on Akala Island, they will be recruited by Anabel and Looker to capture the Ultra Beasts that escaped from the Ultra Wormhole as a form of protective custody. There are five different missions to capture different Ultra Beasts that will take the player to each of Alola four islands. In some missions, there will be multiple of the same species, and in some missions, the Ultra Beast may be able to be found in either of two locations.
When a battle with an Ultra Beast begins, it will be surrounded by an aura that sharply increases one of its stats. To help capturing the Ultra Beasts them, the player is given ten Beast Balls at the start of each mission. Most Poké Balls except the Master Ball and Beast Balls are no more effective than a regular Poké Ball against Ultra Beasts. The Beast Ball, however, is specifically designed to overcome this limitation.
If the player flees from or defeats any of the Ultra Beasts, they can still be found again immediately at the same place (or the alternate location, if applicable and if so desired).
Nihilego
The first mission involves the player capturing a sole Nihilego, also known as UB-01 Symbiont. Nihilego can be found inside Diglett's Tunnel or at Wela Volcano Park.
In Pokémon Sun, the second mission involves the player capturing two Buzzwole, also known as UB-02 Absorption. Buzzwole can be found at Melemele Meadow.
In Pokémon Moon, the second mission involves the player capturing four Pheromosa, also known as UB-02 Beauty. Pheromosa can be found inside Verdant Cavern.
The third mission involves the player capturing two Xurkitree, also known as UB-03 Lighting. Xurkitree can be found inside the Lush Jungle or at Memorial Hill.
In Pokémon Sun, the fourth mission involves the player capturing four Kartana, also known as UB-04 Blade. Kartana can be found at Route 17 and Malie Garden.
The fifth and final mission involves the player capturing a sole Guzzlord, also known as UB-05 Gluttony. Guzzlord can be found inside the basement floor of Resolution Cave.
After completing all five Ultra Beast missions and finishing the storyline at Aether Paradise, the player can find the Legendary PokémonNecrozma in the tall grass at Ten Carat Hill's Farthest Hollow. If the player flees from or defeats Necrozma, it can still be found again immediately.