Recently, Pokemon GO went through another run-of-the-mill update (version 1.23.1 for iOS and 0.53.1 for Android). For the most part, it was just a bug-fix update. Nothing special. But shortly after the updated started rolling out, trainers started noticing something different. In particular, they noticed that Pikachus and Raichus had varying genders.
It was easy to spot. Female Pikachus have a heart shape at the ends of their tails instead of the famously flat end most people know. With Raichus, males have pointier tails while the females are more blunt. Shortly after this discovery, all of these Pokemon reverted back to normal: Pikachus to male and Raichus to female.
The most interesting point of the glitch was that it was present in both caught and wild Pokemon. That means whatever work Niantic is doing to add gender in Pokemon GO is retroactive. That’s definitely a good sign considering the alternative of only having one gender.