From Bulbapedia, the community-driven Pokémon encyclopedia.
This is a list of Pokémon obtainable from events found in the Generation VII Pokémon games. Most of these Pokémon can only be obtained once per game; however, some may also be obtained in other ways as well.
Alola starter Pokémon
After the player is rescued by Tapu Koko, Hala will present the player the three starter Pokémon the player can choose from. Hau will have the starter weaker to the player's choice, while Professor Kukui will have the starter stronger to the player's choice, fully evolved. Gladion's Silvally will also be the type superior to the player's choice, thanks to its Ability, RKS System.
The receptionist of the Pokémon Nursery at Paniola Ranch will give the player this Eevee Egg upon visiting her for the first time. This Eevee has its Hidden Ability, Adaptability.
After becoming Champion, an Aether Foundation scientist inside the Aether House will give the player a Porygon as an apology for the actions of Lusamine and the Foundation. A female Employee in the same room will give the player an Up-Grade.
A female Ace Trainer inside the Huntail-themed boat house in Seafolk Village will give the player an Aerodactyl.
The player can assemble Zygarde 10% Forme and Zygarde 50% Forme on Route 16 on Ula'ula Island out of Zygarde Cores and Cells, which can be collected in the overworld after obtaining the Zygarde Cube. A 10% Forme Zygarde with the Aura Break Ability can be assembled with 10 cells and cores, a 50% Forme Zygarde with Aura Break can be assembled with 50 cells and cores, and a 50% Forme Zygarde with the Power Construct Ability can be assembled with 100 cells and cores. A Zygarde with Aura Break cannot change formes, but a Zygarde with Power Construct can be changed between 10% and 50% Forme using the Zygarde Cube. Zygarde constructed before becoming Champion start at level 30, while Zygarde constructed after becoming Champion start at level 50.
Multiple Zygarde can be assembled at this location as long as the player possess enough cores and cells. 100 cells can be found in the overworld, but the player can accrue additional ones by separating any Zygarde with the Aura Break Ability. A Zygarde separated into cells will be lost forever, and any Zygarde assembled from those cells will be treated as a completely new Zygarde. A Zygarde with the Power Construct Ability cannot be separated.
10% Forme Zygarde
50% Forme Zygarde
When the player becomes Champion, Gladion will give the player a Type: Null as thanks for their help. He will also give them a collection of Silvally's Memories.
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.
After the credits, the player can challenge the other three guardian deities.
After becoming Champion, if the player brings their SolgaleoS/LunalaM to the Altar of the SunneS/Altar of the MooneM, they will discover a portal to an alternate world where the flow of time is changed to that of the other game, affecting time-based encounters and evolutions. In this alternate world, they can find the Lake of the SunneS/Lake of the MooneM, where if they bring their SolgaleoS/LunalaM, they will receive a Cosmog. Because the alternate world does not affect game-based encounters or evolutions, this Cosmog will eventually evolve into another SolgaleoS/LunalaM if not traded.
Solgaleo and Lunala
After confronting Lusamine and rescuing her and Guzma from Ultra Space, Nebby, now a SolgaleoS/LunalaM, will wish to continue growing stronger. However, because Lillie is not a Trainer, she suggest that it join the player's party. SolgaleoS/LunalaM faces the player in battle to test them.
After becoming Champion, the player is recruited by Anabel and Looker to capture the Ultra Beasts that escaped from the Ultra Wormhole as a form of protective custody. The player is assigned five missions, taking them to various parts of Alola to capture one to four of them, dependent on species. When the battle begins, the Ultra Beasts will be surrounded by an aura that boosts one of their stats. To help them, the player is given ten Beast Ball at the beginning of each mission, which are designed to be extremely effective in capturing them. While some Ultra Beasts can be found in multiple locations, they should not be mistaken for roaming Pokémon.
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 Moon, the fourth mission involves the player capturing two Celesteela, also known as UB-04 Blaster. Celesteela can be found at Haina Desert and Malie Garden.
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 Pokémon Necrozma in the tall grass at Ten Carat Hill's Farthest Hollow.