Pokemon Go's female Pikachu have disappeared as quietly as they appeared. Players first noticed Pokemon Go had added the female Pikachu (which have a heart-shaped tail tip) on Tuesday, shortly after the game had announced a new update. Many assumed that the female Pikachu were a sign genders were about to be added to Pokemon Go, but it appears it was a feint.
Earlier today, players noticed that the Pikachu had all converted to males, but that all the Raichu (Pikachu's evolved form) were all female. Later in the day, all the Raichu had also switched back to being male. Oddly, the Raichu also briefly had white Santa hats when they switched back to their male forms.
So what happened to all the female Pokemon? Well, we know that Pokemon Go recently added a debugging system in their code to test future updates related to gender, forms, and shiny Pokemon. It's likely that the Pikachu were just a test run that inadvertently found their way into the live version of the game.
We may never know why Pokemon Go briefly populated female Pikachu, but it's a definite sign that female Pokemon will likely be added to the game in the very near future.