While players are still waiting for the Pokemon Go
update that will introduce Gen 2 Pokemon as well as a trading feature, the title is slowly improving its gameplay through smaller updates. Following the Buddy System that made it easier to get Candy, the latest update will address the spawn rate of three Pokemon that have been affecting the experience of players.
Indeed, as numerous memes and videos will attest, the most common Pokemon in the game were Zubat, Rattata and Pidgey. So common in fact that they were almost always in the nearby Pokemon list. Their spawn slot thus will be occupied by other Pokemon, which should make it easier for players to complete their Pokedex.
Moreover, according to a Twitter post, this update will also affect eggs: "Professor Willow has discovered that Pidgey & Rattata no longer hatch from Eggs. He also found that Eevee now hatches from 5 km Eggs only."