Pokémon GO updated to version 0.53.1 for Android and 1.23.1 for iOS on the 17th of January 2017.
- Updated Apple Watch to display Eggs obtained from PokeStops.
- Changed distance tracking to better account for GPS drift.
- Minor text fixes.
When the update was first implemented, some Pikachu, both already captured and in the wild, could appear to be female. This is indicated by a heart-shaped tail.
Oddly enough, Raichu have always used the female model in Pokemon Go, but they appeared male when viewing the list of Pokemon or the Pokedex list after this update. Male Raichu have a pointy tail, whereas female Raichu have a blunt tail. Some Reddit users reported having both female and male Raichu as well.
The next day, January 19, 2017, glitches began to occur after all Raichu appeared male. Santa Hat Raichu began displaying all white hats instead of red hats.
At the time of this writing, January 19, the servers are down with the assumption Niantic is implementing bug fixes.
During these changes, no other Pokemon appeared to have models differentiating between male and female.