You can now trade specific Pokémon GO Pokémon to evolve them. If you do this, you will save a significant amount of candy and will be able to improve your friendship with the other trainer in the process.
The trading mechanic is pretty simple. All you have to do is trade the Pokémon you want to evolve with another trainer, and then they send them back to you to give you their new evolved form. However, this doesn't work for all Pokémon. There are only a handful that it works on. Here is the list of Pokémon you can evolve through operations:
If you have any of these Pokémon in your collection, contact another trainer you trust to trade with them. You need to be in close proximity to them to trade.
This list is not the ending. Niantic developers are likely to increase this list as time passes and more Pokémon come into play. We can expect more Pokémon already in the game to receive this because a handful of them in the original Pokémon titles require you to swap them in order to evolve. We don't know when this will happen. We will update this list as we learn about others and can expect it to become a new Pokémon GO staple.