Abilities - The Basics
Starting with the Generation III games Pokémon Ruby and Sapphire, each Pokémon received an Ability that would activate under certain conditions. They served to give Pokémon new uses and powers that allowed them to fill brand new roles for a team. Some abilities are beneficial to the Pokémon, while others hinder the user to prevent them from being too powerful. Abilities are not directly manipulable by the player, like Individual Values. Some Pokémon also have Hidden Abilities, which are Abilities that they can't normally have if found in the wild.
Manipulating Abilities
Pokémon with more than one Ability are given one at random when found in the wild, and the player cannot manipulate this in any way. However, Abilities are passed down through Breeding, and the player can indirectly influence what the offspring's Ability will have.
Starting from the Generation V games Pokémon Black and White, when breeding Pokémon, the offspring has an 80% chance of having the same ability as its mother.
The Generation VI games Pokémon X and Y introduce an item called the Ability Capsule that allows the player to change a Pokémon's ability to its other regular Ability. This, however, does not allow the player to change the Ability to a Hidden Ability.
Starting from the Generation V games Pokémon Black and White, when breeding Pokémon, the offspring has an 80% chance of having the same ability as its mother.
The Generation VI games Pokémon X and Y introduce an item called the Ability Capsule that allows the player to change a Pokémon's ability to its other regular Ability. This, however, does not allow the player to change the Ability to a Hidden Ability.
Notable Abilities
There are a total of 188 Abilities as of Pokémon X and Y. Listed below are some of the more popular ones and some of their more notable users.
Intimidate
Pokémon with Intimidate will lower the Attack stat of the opposing Pokémon in battle every time the user switches in. This allows the user to cripple the power of potent, high-offense threats. Below are some noted users of the Intimidate Ability:
Synchronize
If a Pokémon with Synchronize is hit with a status effect (Paralyze, Poison, Burn, etc.), the opposing Pokémon will be hit with the same status effect. This allows the user to even the playing field if the opponent tries to gain an upper hand by inflicting status effects. Below are some noted users of the Synchronize Ability:
Sturdy
If a Pokémon with Sturdy at full health is hit with an attack that would normally KO them, they will survive with 1 HP. This guarantees them to always do at least one action before they fall in battle.
Further Reading
Click HERE for a more in-depth explanation of how Abilities work on Bulbapedia, including a list of all Abilities found in the game.