Plus powers up with Minus. When a Pokémon with Plus enters into a Double Battle with a Pokémon with the Ability Minus, the user's Special Attack stat is increased by 50%.
Generation V onward
When a Pokémon with Plus enters a battle and has an ally with Plus or Minus, the Special Attack stat of the Pokémon with Plus is increased by 50%.
A Pokémon with this Ability will receive a 50% bonus to Special Attack when using a special move if an allied Pokémon with the Ability Minus is nearby. Since Gates to Infinity, the Ability also activates if an allied Pokémon with the Ability Plus is in the same room.
Raises Special Attack when an ally with the Plus or Minus Ability is nearby.* If a teammate in the same room has the Plus or Minus Ability, the Pokémon's Special Attack will go up!*