Part of this new friend system for Pokemon Go includes the option to actually trade Pokemon with your friends. In order to initiate Pokemon Go trading you’ll need to fulfil the following requirements:
1) Be Pokémon Go Friends with the person you want to trade with
2) Have a Trainer Level of 10 or above
3) Be basically next to the person you want to trade with in real life, aka within 100m
Other than that, you need to take into consideration that it costs Stardust to trade Pokemon, and a Pokemon’s HP and CP will change when it’s traded. You can view what the changes will be before you trade, but it’s worth checking because you could get a high-level Pokemon seriously changing if you’re trading with a player of a much lower level. You can’t trade mythical Pokemon like Mew though, and anything of a shiny or Legendary variety will be much more expensive and can only be traded once per day.