Pokémon in this event
Pikachu
Espeon
Umbreon
Beedrill
Clefairy
Gengar
Staryu
Houndoom
Sableye
Manectric
Drifblim
Elgyem
Rockruff
Applin
Maschiff
Bramblin
What changes for your raids
From Tuesday, November 24, at 10:00 a.m. to Monday, November 30, at 8:00 p.m. local time, Twilight Wishes dresses up the raid bosses. One-star raids: Pikachu wearing a sun crown or a moon crown. Three-star raids: Espeon wearing a sun scarf, and Umbreon wearing a moon scarf. All of them can be shiny. Espeon is a Psychic-type and takes extra damage from Bug, Dark, and Ghost attacks; Umbreon, a Dark-type, is weak to Fighting, Bug, and Fairy.
Mega Raids bring Mega Beedrill, Mega Houndoom, Mega Sableye, and Mega Manectric, shiny possible too. Plan on 100 Mega Energy per Pokémon for a first Mega Evolution; the GO Pass hands out Mega Energy for Beedrill, Houndoom, Sableye, and Manectric. Our calculations give two to three Trainers to beat Mega Sableye.
The GO Pass is free and arrives automatically on the first day. At Rank 1, trades give Lucky Pokémon more often, and Lucky Friends come faster. At Rank 10, catching Pokémon gives 2× Stardust, and 3× with the GO Pass Deluxe. The Deluxe costs US$4.99 (or local equivalent); the version that takes you straight to Rank 7 costs US$6.99 (or local equivalent). Claim your rewards before Wednesday, December 2, at 8:00 p.m. local time.
The rest: Clefairy, Staryu, Elgyem, and Rockruff appear in the wild, shiny possible. Shiny Staryu and Shiny Elgyem show up more often during the event; look for Staryu (Water) in rainy weather and Elgyem (Psychic) in windy weather. Field Research gives Mega Energy, plus Applin and Maschiff through November 26 at 10:00 a.m., then Gengar wearing a Spooky Festival costume, Drifblim wearing a Halloween Mischief costume, and Bramblin. Full details in the official announcement.