You can’t catch the invading, scary bones in Pokeball, but if you’re looking to celebrate Halloween, then Niantic has something planned for you.
Pokemon GO will have a Halloween 2020 event that will take place from October 23 to Novem ber 3
Gengar and Sableye get Halloween costumes. You can find the first one by invading, and the last one either by eggs or by meeting them in a wild battle. Spiritomb can be found through regular research, and you’ll have a chance to discover something Shiny.
In the meantime, some special research projects called “A Spooky Message Unasked” can get you a Galarian Yamask, and you can find Mega Gengar with an outdated research by collecting Gengar Mega Energy.