I got rid of my cellphone, so I haven't played in a while, and not at all during this event -- but in the months I was playing I had seen all of TWO total wild-spawned Chansey. And the two places I've played, in two different states, are both annoying low on fire types (sole exception being a tendency towards ponyta /nests/, and it seems like there's always that ONE off-biome nest thrown in for mercy....)