Raid Battle

A Raid Battle is a special event that takes place within a Gym in Pokémon GO.

Background
A Raid Battle is a cooperative gameplay experience that encourages Trainers to work with other Trainers to defeat an extremely powerful Pokémon known as the Raid Boss. Before a Raid Battle begins, all Pokémon assigned to the Gym will return to their owners, and a large Egg will appear atop the Gym. When the countdown above the Egg reaches zero, the Raid Boss will be revealed.

There is also a special Raid called an EX Raid Battle is an invitation-only. A trainer will receive a notification along with with time, date and location; along with an Exclusive Raid Pass to gain entry into the Raid.

They seem to only run between 6:00AM (starting time) and 9:00PM local time.

Raid Pass
Before a Trainer can battle the Raid Boss, they'll need a Raid Pass. Trainers can receive one free Raid Pass per day by visiting a Gym, but can only hold one at a time. A Premium Raid Pass may also be purchased from the in-game Shop.

Raid Boss
Upon using a Raid Pass to join the battle, the Trainer and up to 20 other Trainers work together to defeat the Raid Boss. If a Raid Boss is successfully defeated within the five-minute time limit, those Trainers have the chance to catch an extra powerful Pokémon of their own.

Rewards
After defeating a Raid Boss, Trainers receive a collection of rewards, including some new items obtained only by defeating a Raid Boss: Rare Candies, Golden Razz Berries, and Technical Machines.

Bonus Challenge
After successful defeating of Raid Boss and being rewarded with Items, there are Raid Battle statistics shown to Trainer with amount of Premier Balls given to them. Then player can go to Bonus Challange, which is oportunisty of catching Raid Battle as if it was a Pokémon in the wild, but with a significant difference which is that player doesn't have their currently owned Poké Balls for use but only these Premier Balls, that they have been rewarded for performance in won Raid Battle.

History

 * 23rd June - Raids were open being available for players level 35 and above
 * 23rd June - Raids were made available for players level 31 and above
 * 23rd June - Raids were made available for players level 28 and above
 * 24th June - Raids were made available for players level 25 and above
 * 26th June - Raids were made available for players level 20 and above
 * 1st July - Raids were made available for players level 5 and above