Ability₁₄₁-Minus

Minus powers up with Plus (And Minus in later Generations).
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⚠️When a Pokémon with Minus enters into a Double Battle with a Pokémon with the Ability Plus, the user's Special Attack stat is increased by 50%.
🔵Gen⁵⁺
When a Pokémon with Minus enters a battle and has an ally with Plus or Minus, the Special Attack stat of the Pokémon with Minus is increased by 50%.
🧲The move Magnetic Flux raises the Defense and Special Defense of allied Pokémon with Plus or Minus by 1 stage.
⚙️Gear Up raises the Attack and Special Attack of allied Pokémon with Plus or Minus by 1 stage.
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~Bulbapedia