Pokemon GO Halloween 2020 runs from October 23 at 9 p.m. EST through November 3 at the same time and offers the first chance to get your hands on Galarian Yamask among other things.
Completing the Halloween Special Research "A Spooky Message Unmasked" gets you one step closer to finding both Galarian Yamask and Spiritomb. Other Field Research tasks will also center around Halloween themes during the event.
Ghost-type Pokemon will be more common in the wild, in Raids, and in Eggs. You might even find a costumed Gengar in Raids or hatch a Sableye in costume if you're lucky.
Talking of Raids, Darkrai takes center stage for five-star Raids, but there's more Halloween Raid goodness in store.
On October 31 from 11 a.m. local time through 5 p.m. local time, there's a higher chance Alolan Marowak will show up in Raids.
There's a special Halloween Cup from October 26 at 4 p.m. EST through the end of the event where only Poison, Dark, Bug, Ghost, and Fairy Pokemon can compete, and they have to have less than 1,500 CP.
It just wouldn't be Halloween without costumes. Pokemon GO Halloween 2020 amps up the costume game with a Gengar onesie, Sableye goggles, Pikachu mask, and more, along with bundles in the in-game shop.
Finally, there's an all-new event on October 26, the Catch Mastery event, which we cover in more detail elsewhere.