How do I trade or add friends in Pokemon Go? Or is it not possible yet? For instance, each Pokemon has a "Transfer" option, but it seems that only gives the Pokemon to the professor, not to other players.
Trading is coming to Pokemon Go in the next update with the new friend feature. You will be able to trade Pokemon with a friend that is in close proximity with you. The trade will cost stardust and Pokemon IVs will change in the trade. The higher your friend level with another player is the less stardust trading costs and the less IVs will be able to alter. If the Pokemon is caught further that 100km from the trade location trading will give extra candies. This answer is based on Rankedboosts summary of the coming features.