Berries

Berries are items that can be acquired from leveling up, spinning the Photo Disc at a Gym or PokéStop, defeating a Raid Boss, completing research tasks, opening Gifts, or GO Battle League. They can be used while capturing wild Pokémon. They can also be fed to a Pokémon in a friendly Gym, increasing its motivation and CP. 20 Stardust is earned per berry fed to Gym Pokémon, and Trainer can feed one up to 10 berries at a time. Berries can also be used to feed Pokémon since the Buddy Adventure update.

There are currently five kinds of berries available in gameplay:
 * Razz Berry,
 * Pinap Berry,
 * Nanab Berry,
 * Golden Razz Berry
 * and Silver Pinap Berry.

To see currently owned Berries Trainer can check them out on the item bag page.

Update history
Before the GO Beyond update, the effectiveness of certain Berries were weaker:
 * Nanab Berry only slowed down a Pokémon for 95%
 * Silver Pinap Berry doubled the amount of Candy like regular Pinap Berry
 * Buddy changes - to be added

Trivia

 * The in-game description of the item is misleading. It states that feeding Razz Berry to a Pokémon "on your next throw" will make it easier to catch. The effect actually lasts until the Pokémon enters a Poké Ball at least once. If the Pokémon seems to be captured, but escapes the ball, the effect of the berry wears off, and another must be used. If the Pokémon does not enter the ball, such as if the player's throw misses, the effect does not disappear.
 * Also, only one berry can be used at a time. After an unsuccessful capture (Pokémon escapes from Poké Ball), the effect of berry wears off and the player may use another berry.
 * The following berries' names are based on names of real fruits:
 * Razz Berry is named after raspberry.
 * Nanab Berry is banan(a) spelled backwards.
 * And Pinap Berry is pun of berry and pineapple
 * In the original handheld series, Nanab Berries increase the cuteness of a Pokémon.
 * Nanab berries originally slowed a Pokemon by 70%.
 * Originally in game data pictures for Nanab and Pinap Berry were recolored versions of sprites of Wepear and Bluk Berry, as:
 * sprite for Nanab Berry was red-colored Bluk Berry sprite
 * and sprite for Pinap Berry was green-colored Wepear Berry sprite.
 * A berry known as the "ChocoNanab" appears in the game's files. This appears to be a Nanab Berry that is half-covered in chocolate.