Details: After defeating
Anabel, she and
Looker will send you to Ms. Wicke on
Aether Paradise, who is cooperating with
The International Police after all the trouble
The Aether Foundation caused. Go to Wicke, and she will initially not tell you anything about the
Ultra Beasts, but rather the true reason why
Lillie chose to go to the Kanto Region with her mother.
Wicke goes on to say the
Lillie picked Kanto specifically because she read a book once that described how a trainer was once turned into a Pokemon like her mother, but was able to be turned back to normal by using his cell separation machine. The trainer is none of than Bill, and she went with her mother to Kanto to seek his help in possibly
Healing her.
After this, Wicke will turn and walk away in the Labs Area of the
Aether Paradise. Follow her, and she will eventually give you a number of Beast Balls. These special
Poke Balls work well on
Ultra Beasts - having a x5 Catch Rate to be exact - but aren't good on any other species. After receiving them, you must return to
Anabel and
Looker in the hotel on
Route 8.
Talk to
Anabel, and
Looker will quickly burst into the room, saying there has been sightings of UB-01 Symbiont in both
Diglett Tunnel and
Wela Volcano Park. They ask you then to go to one of these areas and find it.
Nihilego can be found randomly in the wild
Grasses and cave, like all the
Ultra Beasts, and the music will change when you are nearing in on it. (You only need to catch on of its species.) UB-01, whose real species is known as Nihilego, will be at Level 55, knowing the
Moves Power Gem, Mirror Coat, Acid Spray, and Venom Drench. It's a Rock / Poison Type Pokemon.
Like all the
Ultra Beasts in this storyline,
Nihilego will have one of its
Stats doubled immediately as the
Battle begins. It, specifically, will have its Special Defense increased. It also has the ability of Beast Boost, which will further boost its best
Stat each and every
Time it knocks out one of your Pokemon.
Catch
Nihilego, and your first mission is now complete. Head back to
Looker and
Anabel to inform them of this, and to receive your next mission.