Poké Balls are items that are critical to a Trainer's quest, used for catching and storing Pokémon. Currently Poké Balls can be obtained through several different ways such as: spinning Photo Discs at Gyms and PokéStops, being rewarded for leveling up, completing research tasks, opening gifts or purchasing them in Shop (in this case only regular ones).
There currently five varieties of Poké Balls exist in-game:
When encountering a Pokémon in the wild, players can attempt to catch a Pokémon by holding down on the Poké Ball, sliding upwards, and letting go to launch it towards the Pokémon.
Players can influence bonuses on catching Pokémon by aiming the ball towards the center of the Pokémon while letting the circle indicator shrink down. The closer the ball is to the center, the better bonus you'll get. Players can also hold down the ball and spin it for a curveball bonus that grants additional experience. Selecting a better type of Poké Ball will make the Pokémon easier to capture.
It is high-performance Poké Ball that increases Trainer's chance of capturing a Pokémon by 50%.
Great Balls are unlocked once the player hits Level 12. Upon levelling to 12 the player receives 20 free Great Balls and they become available via spinning Photo Discs. This kind of Poké Ball is a reward for levelling up from levels 12 to 19.
In-game description A good, high-performance Poké Ball that provides a higher catch rate than a standard Poké Ball.
It is high-performance Poké Ball that increases Trainer's chance of capturing a Pokémon by 100%.
Ultra Balls are unlocked once the player hits Level 20. Upon leveling to 20 the player receives 20 free Ultra Balls and they become available via spinning Photo Discs. This kind of Poké Ball is a reward for leveling up from levels 20 to 40.
In-game description An ultra-high performance Poké Ball that provides a higher Pokémon catch rate than a Great Ball.
Based on which Trainers controlled the Gym, how much each Trainer contributed as a team during the Raid Battle, each Trainer will receive a variable number of Premier Balls. These can be used to capture the Raid Boss, once it has been defeated.
Unused Premier Balls are discarded after a Raid Boss encounter.