Ability₁₆₉-Plus

Plus powers up with Minus (And Plus in later Generations).
----------------------------------------------------------------------------------------------------------------------------------------------------------------
⚠️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%.
🔵Gen⁵⁺
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%.
🧲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.
---------------------------------------------------------------------------------------------------------------------------------------------------------------
~Bulbapedia
--------------------------------------------------------------------------------------------------------------------------------------------------------------
Damage To Victini in example:
With Plus: 176ₕₚ➡️122ₕₚ
Without Plus: 176ₕₚ➡️149ₕₚ