Gorilla Tactics boosts the Pokémon's Attack by 50%, but limits the Pokémon to using only one move, similar to the Choice Band. This effect stacks with Choice items, meaning a Pokémon with this Ability and a Choice Band will have its Attack boosted by 125%.
Gorilla Tactics temporarily stops working if the user is Dynamaxed.
Outside of battle
It is unknown if Gorilla Tactics has an effect outside of battle.