It was recently announced on the official Pokémon website that a “major” update is coming to Pokémon GO that will include new mechanics for Gym battles and something called Raid Battles.
Gyms are about to get a huge overhaul and in anticipation of this, all Gyms are temporarily shut down. After “construction” ends, Gyms will be very different. For one thing, you will be able to get items at Gyms the way you can only get them at PokéStops currently. Also, Gyms will only be able to hold six Pokémon, instead of the ten it has been, and challengers will battle these Pokémon in the order they were assigned to the Gym, rather than in order of increasing CP. A new “motivation” mechanic will be added which will cause Pokémon at Gyms to lose motivation every time they are defeated, even if the Gym itself is not defeated. When a Pokémon‘s motivation is reduced completely, it will return to its trainer. You can raise a Pokémon‘s motivation by giving it berries. There will also be Gym Badges added to the game, which will allow you to get different items from Gyms depending on how high of a level your Badges are. You can increase the level of your Badges by battling at Gyms, giving berries to Pokémon and collecting items from Gyms.
Another new mechanic, called Raid Battles, will also be coming in this update. A Raid Battle will comprise of up to twenty players taking on one, super-powerful Pokémon with CP in the 20,000s called a Raid Boss. Trainers on different teams can unite to take on Raid Bosses, and once a Raid Boss is defeated, winning players will get special items as well as the opportunity to catch the Raid Boss. Special items that can only be received through winning Raid Battles include Rare Candies, which are Candies that can be used on any Pokémon, Golden Razz Berries, which can be used to greatly increase the catch rate of a wild Pokémon or fully restore the motivation of a Pokémon at a Gym, and Fast TMs and Charged TMs, which will replace a Pokémon‘s Fast or Charged attacks at random. To participate in Raid Battles, Players will need a Raid Pass, which you can receive one of a day by visiting a Gym. Note that you can only hold one Raid Pass at a time, so you can’t stockpile them and then participate in a bunch of Raid Battles.