The moment Pokémon Go players thought would never come is here. Trading has been added to the game. But it's not like trading from the good ol' days of Pokémon. Trainers can't just pick any Pokémon they feel like and exchange for whatever their heart desires. This is a mobile game, and so it imposes a few conditions to prevent players doing too much too fast. To stop trainers from filling up their whole Pokédex in a day, Niantic made Pokémon Go's trading system dependent on another new function: the Friends List.
How To Make Friends
Before you can even think about trading, you have to have a friend to trade with. Exchanging Trainer Codes will get the process started, but there's more to do after that. There are four increasing ranks of friendship: Good Friend, Great Friend, Ultra Friend, and Best Friend. Like many other things in Pokémon, grinding is required to turn a Good Friend into a Best Friend. Raising friendship levels is done by sending gifts to each other, trading, battling gyms together, and doing raids together.
Becoming better friends has its benefits. For each rank you achieve with an individual friend, the more bonuses you'll receive from that person. These range from bonus balls in raids you do together to discounts to the cost of trading rare Pokémon with one another. The detailed list of bonuses are:
Good Friend: Unlocks the ability to trade everything but Mythical Pokémon
Great Friend: Discount of Stardust for trading, damage bonus during gym battles fought together, one extra Premiere Ball for raids done together
Ultra Friend: Even greater Stardust discount for trading, a higher damage bonus for gym battles, two extra Premiere Balls for raids done together
Best Friend: Huge Stardust discount for trading, the highest damage bonus in gym battles, four extra Premiere Balls for raids done together
It was specified by Niantic that these bonuses do not stack. Only the highest-level friend's effects are taken into account. So if you raid with a Best Friend and two Great Friends, only the Best Friend's damage and Premiere Ball bonuses will be given. Friend Lists will be capped at 200 friends to begin with, and potential increases are not something Niantic is looking to charge for.
Mystery Gift But With More Alola
Before you trade, why not get some stuff for free? You'll now have the ability to send gifts to your Pokémon Go friends, and get some in return. The gifts will randomly drop from PokéStops. You can send them to anyone on your Friends List, and doing so will work towards increasing your friend rank. The gift will open to reveal one of the rarer items dropped from PokéStops like Revives or Max Potions and a cute little postcard of the PokéStop it came from.
But perhaps the most enticing gift will be the new 7km egg. These are guaranteed to hold one of the fan-favorite Alolan Form Pokémon like icy Vulpix or Diglett with hair. Overall, the function acts like the Mystery Gift feature from the main games, and will be an exciting way to build friendships and get decent items.
Now for the moment everyone's been waiting for. How does trading work? The short of it is that it requires the parties be friends and be within 100 meters of one another. Both trainers must also be at least level 10. Trading will cost Stardust, the amount depending on the rarity of the Pokémon and the friendship level of the trainers. Giving up a Pokémon will reset its HP, CP, and even IVs. This actually makes it so that a traded Pokémon can become stronger for its new trainer. The likelihood of getting better stats will increase with higher friendship level.
There is one important restriction on trading. Legendary Pokémon, Shiny Pokémon, and Pokémon not recorded in your Pokédex can only be traded once per day. These are categorized as Special Trades. Special Trades are presumably a once a day affair to prevent players from catching 'em all too quickly. And that once a day means in total, even if you have more than one friend.