What do I do with all these Chansey now?
http://www.nintendoworldreport.com/news/48608/pokemon-go-gets-gen-4-and-rebalance
Sinnoh Pokémon and stat balances will come “soon” to Pokémon Go, Niantic announced today.
Gen. IV's Diamond, Pearl, and Platinum introduced 107 Pokémon, some of which expanded evolution lines for previous Pokémon. Electabuzz, Rhydon, Magmar, and Eevee all have Gen. IV evolutions.
Gameplay balances will address player feedback, Niantic said. CP, Defense, Stamina, and HP adjustments aim to lower the gaps between Pokémon.
A greater variety of Pokémon will appear, softening the impacts of weather, habitats, and nests.