Arbok

When this Pokémon enters battle, the opponent's Attack is lowered by one stage. In a double battle, both opponents are affected. This ability also takes effect when acquired during a battle, but will not take effect again if lost and reobtained without leaving battle. This ability has no effect on an opponent that has a substitute. Overworld: If the first Pokémon in the party has this ability, any random encounter with a Pokémon five or more levels lower than it has a 50% chance of being skipped.