Hidden Abilities are special rewards obtained by participating in Max Raid Battles. At the start of the game you will receive a Dynamax Band which will allow you to take part in it. As you play, you will come to the wild area and then you can start exploring Max Raid Battles.
How to get hidden abilities in Pokémon Sword and Shield
In the wild area, you will notice glowing rock formations emitting a beam of red light. These are active spots from Max Raid Battle. Interact with them to queue up with other players. It is possible to play solo with nice artificial intelligence players, but it is more fun to play with fellow coaches.
You will need to defeat and catch the enemy of Max Raid battle. Sometimes these Pokémon can have hidden abilities, but this is a random reward. You may need to grind Max Raid Battles to get a Pokemon with such an ability.
The reason they are called hidden abilities is that they are hidden from you, although they are active on Pokémon that have them. At this time, there is no indication that the hidden abilities can be passed on to the descendants of Pokémon.
List of hidden abilities
Below is a list of hidden abilities. The list is not exhaustive and will be updated as more hidden abilities are discovered.
Fearless shield
Strengthens the defense of Pokémon when entering a battle.
Grassy Surge
Turns the ground into grassy terrain when the Pokémon engages in battle.
Gulp Missle
When the Pokémon uses Surf or Dive, it returns with prey. Prey is spat out to attack when the Pokémon takes damage.
Hunger switch
Pokémon change shape from full belly mode to hanging mode, or vice versa, at the end of each turn.
Ice face
The Pokémon can absorb an attack with its head, changing its appearance. Ice damage used to absorb the hit will be restored upon healing.
Ice flakes
The protective ice scales will be damaged by special movements.
Fearless sword
Increase attack stats when the Pokémon enters battle.
Libero
Changes the type of Pokémon depending on the type of movement it is about to use.
Mimicry
This will change the type of Pokémon depending on the type of terrain the battle is being fought on.
Mirror armor
Any stat reduction effects used on the Pokémon will be deflected towards the attacker.
Body perish
When attacked by a move making direct contact with the Pokémon, kick it and the attacker will pass out after three turns if not disconnected.
Power spot
The proximity of the Pokémon reinforces the movements.
Propeller tail
Effect unknown at this time
Sniper
Critical hits will fuel a movement.
As soon as we can confirm more Hidden Abilities, or which Pokémon have them, we'll update this guide accordingly.