In a traditional Pokemon game, players evolve their Pokemon by leveling them up through hours of Pokemon battles. Since battling is de-emphasized in Pokemon GO, the game uses a different way to evolve Pokemon: specialized candies that can be used to power up and evolve Pokemon. The process is pretty simple, but here's a few tips to make evolving your Pokemon as efficient as possible.
Players get candy every time they catch or hatch a Pokemon, so it's in your best interest to catch literally every Pokemon you find. It's also a good idea to "transfer" (AKA get rid of) any Pokemon you don't want, as you get an extra Candy when doing so. You'll also get the same type of Candy for any Pokemon in the same evolutionary line. So, for instance, catching and releasing a Kakuna will get you a total of 4 Weedle Candy. Here's how many Pokemon you'll need to catch and release to fully evolve certain types of Pokemon:
7 Catch and Transfers: Rattata, Eevee
13 Catch and Transfers: Spearow, Ekans, Pikachu, Sandshrew, Clefairy, Vulpix, Jigglypuff, Zubat, Paras, Venonat, Diglett, Meowth, Psyduck, Mankey, Growlithe, Tentacool, Ponyta, Slowpoke, Magnemite, Duduo, Seel, Grimer, Shellder, Drowsee, Krabby, Voltorb, Exeggcute, Cubone, Koffing, Rhyhorn, Horsea, Goldeen, Staryu, Omanyte, Kabuto
16 Catch and Transfers: Caterpie, Weedle, Pidgey
25 Catch and Transfers: Ivysaur, Charmeleon, Wartortle, Metapod, Kakuna, Pidgeotto, Nidorino, Nidorina, Gloom, Weepinbell, Poliwhirl, Kadabra, Machoke, Graveler, Haunter, Dragonair
32 Catch and Transfers: Bulbasaur, Charmander, Squirtle, Nidoran (both Male and Female), Oddish, Bellsprout, Poliwag, Abra, Machop, Geodude, Gastly, Dratini
100 Catch and Transfers: Magikarp
It's also important to point out that evolving Pokemon will give them a big boost in CP. So, it may make more sense for you to evolve a more powerful Pidgey than it is to evolve a weak Pidgeotto. If you want to get a sense how strong a Pokemon is, you can check how strong a Pokemon is by looking at the arc above the CP. The further the white dot is to the right, the more powerful your Pokemon is.
It also makes sense to wait to spend your candy to power up a Pokemon until it's fully evolved. Evolving Pokemon will randomly change your Pokemon's moves, so you don't want to power up a Pokemon and then see it get weak moves when it evolves.
One other important note: Eevee's evolutions are totally random. Eevee will evolve into either a Jolteon, a Vaporeon or a Flareon, but you don't get to pick how it evolves. Supposedly, all three Eeveelutions appear in the wild when you reach a certain level, so don't despair if you don't get the evolution you want on the first try.
If you're ready to evolve a Pokemon, consider using a Lucky Egg first. Evolving a Pokemon gives you 1000 XP, and a Lucky Egg will cause that XP do double to 2000 XP.
Hopefully, these tips will help you evolve your Pokemon a little bit quicker and help you get some powerful Pokemon!
Pokemon GO is out in the United States, Australia, and New Zealand.