https://www.gamespot.com/articles/pokemon-go-leak-further-points-to-generation-3-pok/1100-6454130/

While we still don't have any official details on what to expect from Pokemon Go's upcoming Halloween event, there's now more evidence that it'll introduce a couple of new Pokemon. The iOS App Store inadvertently shared an image presumably for the event that features some Ghost-type Pokemon, including a couple that aren't currently available in the game.

The new image (via Eurogamer) shows four Ghost Pokemon, most notably the Generation 3 monsters Duskull and Sableye. This certainly lends more weight to the recent datamine that suggests certain Gen 3 Pokemon would be added soon to the popular AR game. The image also features a Pikachu wearing a witch's hat, which will likely only be available to catch during the Halloween event. You can see it below.