Friends

Friendship is a gameplay feature in Pokémon GO which allows for cooperation amongst Trainers for a wide range of activities, including gifting and trading.

Details
Once a Trainer shares their Trainer Code with someone, that person can then send them a Friend Request. Friends can be made regardless of Teams. After two Trainers have become friends, they can send each other Gifts. Gifts are initially obtained by spinning the Photo Disc at a PokéStop or Gym. Trainers can level up their Friendship Level between the two of them once per day by interacting with each other through a variety of in-game actions.

Friends list
The Friends list contains a Trainer's friends. Each Trainer can have up to 400 friends. The list can be sorted by recent activity, online status, name, nickname, friendship level, which friends sent you a Gift, and which friends are eligible to be sent a Gift. Double-tapping a sorting option will reverse the sort order. Friends cannot be set as a favorite. There is no way to contact friends via in-game messages, so you must have some other channel of communication.

Filtering by name/nickname
You can search your friends by typing their name or nickname like a normal text search. It returns those friends whose name or nickname matches the query. This search does not search for sub-strings, so the first part of the name or nickname must be supplied.

Filtering by keywords
There are special keywords that can be used to filter your Friends list. Using these can improve leveling your progress with most of your friends.

General Friend levels

Friendship levels
Once per day, Trainers can interact with each other to increase the total number of unique days they've done so. Once this number reaches certain thresholds, their Friendship Level will increase. Different levels of Friendship will unlock various bonuses for each Trainer. These include Stardust discounts when Trading Pokémon, a bonus attack multiplier when batting in a Gym or Raid Battle together, and extra Premier Balls during the Bonus Challenge of Raid Battles.

In-game interactions that count towards increasing Friendship Levels include:
 * Opening a Gift
 * Trading a Pokémon
 * Battling together in Gym or Raid Battle
 * Challenging each other in a Trainer Battle

Gifting
When receiving a Gift from a friend, Trainers will see a postcard from the PokéStop or Gym where the friend acquired the Gift. Trainers are rewarded with 200 XP for sending Gifts.

Trading
Once two Trainers become friends, they may being trading Pokémon with each other.

Lucky Friends
When a Trainer becomes Lucky Friends with someone, the next time they trade with each other, both Pokémon are guaranteed to be Lucky Pokémon.

To become Lucky Friends, both Trainers must already be Best Friends. Both Trainers will have a chance once per day to become Lucky Friends after their first in-game interaction of the day. Both Trainers will receive a notification when they have become Lucky Friends and will be able to see that they are Lucky Friends in their Friend List and on their friend's profile page.

The odds of becoming a Lucky Friend have been observed to be about 1.17%.

After completing the trade, the Lucky Friend status will return to Best Friend status. There is no limit to how many times you can become Lucky Friends with the same Trainer.