Eevee now hatches out of a five-kilometer egg in Pokemon GO, no Rattata/Pidgey in eggs
Update: Niantic has further clarified the situation with a tweet, stating that in addition to Eevee being limited to five-kilometer eggs, players will no longer recieve Rattata or Pidgey from their hatched eggs. Furthermore, players will find different Pokemon where Zubat, Rattata and Pidgey were commonly found prior to this update.
Professor Willow has discovered that Pidgey & Rattata no longer hatch from Eggs. He also found that Eevee now hatches from 5 km Eggs only.
— Pokémon GO (@PokemonGoApp) November 3, 2016
Professor Willow has discovered that you may encounter other Pokémon where Pidgey, Rattata, and Zubat were previously more commonly found.
— Pokémon GO (@PokemonGoApp) November 3, 2016
Original: Niantic recently made a change to Pokemon GO which is going over very well within the community. In the past, Eevee was a part of the random rotation of Pokemon that could be inside the 10-kilometer egg. Now, however, the Pokemon hatches out of a five-kilometer egg.
It takes quite a bit of work to earn a 10-kilometer egg. After hatching it and learning that Eevee was inside, some players ended up being disappointed as it’s a fairly common creature. With the update, it takes half as many steps to possibly hatch an Eevee or another less rare Pokemon on the same egg tier.