These are abilities which make the Pokémon be immune to certain moves.
The Pokémon's attack statistic cannot be lowered by the opponent's moves (such as Growl or Charm). Compare to Big Pecks, Clear Body, and White Smoke. In Pokémon Emerald, if a Pokémon with Hyper Cutter uses the HM Cut in the field, more grass will be cut than usual.
The Pokémon's attack is raised when struck by a Dark-type attack. The Pokémon does still take damage from the attack. Compare to use of items like Cell Battery and Absorb Bulb.
The Pokémon will not receive damage from Ground-type attacks, as if one of its elemental types was but without the rest of that type's weaknesses and resistances. It will also not be affected by the Arena Trap ability, nor receive damage from Spikes or Toxic Spikes when it enters or leaves battle. Compare to Wonder Guard.
The Pokémon's speed is raised when struck by an Electric-type attack. The Pokémon takes no damage from the attack.
The Pokémon's attack is raised when struck by a Grass-type attack. The Pokémon takes no damage from the attack.
The Pokémon is unaffacted by all attacks which are based on loud sounds and noises. These attacks are:
The Pokémon will take all Water-type attacks, takes no damage, and gains a Special Attack boost as of Generation V. Compare to Lightningrod.
In Generation V, a Pokémon with Sturdy will not die in one hit. Instead, the Pokémon always has one HP left if the attack is one hit kill for that Pokémon.
The Pokémon recovers 1/4 of its total HP when struck by an Electric-type attack. Compare to Water Absorb.
The Pokémon recovers 1/4 of its total HP when struck by a Water-type attack. Compare to Volt Absorb.
The opponent's moves that lower statistics (like Growl, Leer or Scary Face) have no effect. Compare to Big Pecks, Clear Body, and Hyper Cutter. In Pokémon Emerald, if a Pokémon with White Smoke is put first in the trainer's team, the chance of encountering a wild Pokémon is halved.
The Pokémon only receives damage from attacks which are super effective against its type(s). Compare to Levitate.
Before Generation VI, if someone were to hack their game to give Spiritomb or Sableye the Wonder Guard ability, they would become immune to all attacks because of their typing; however, they are still vulnerable to secondary damage (sandstorm, poison, etc.), as well as moves such as Beat Up, Bide, and Doom Desire.