Without getting into the messy details, here’s what you need to know: There are nests scattered around the world where specific Pokemon are more likely to spawn. For example, if you hang around a Charmander nest for long enough, you’re eventually going to see a Charmander spawn on the map.
Over the past day or so, reports have been springing up on The Silph Road that Pokemon evolutions are now spawning at nests, which wasn’t possible previously. In other words, you might find a Charmeleon or even a Charizard at that Charmander nest, but it’s still unclear how likely they are to spawn.
“I have had all the nests in SA/Austin fixed and monitored for the past 4 hours and the scanner is showing Sandslashes at Sandshrew nests, Nidorinos at Nidoran nests, etc.,” says Redditor carypalmer on The Silph Road.
The dedicated Pokemon Go researchers are still hard at work to figure out exactly what this means, but providing it’s true, you should be able to find evolved versions of your favorite Pokemon far more often in the wild from now on.