The description for Gorilla Tactics reads, “Boosts the Pokémon's Attack stat but only allows the use of the first selected move.” By how much does the Attack stat get boosted? For example, 1.3x, 1.5x, 2x,?
The damage multiplier for Gorilla Tactics is 1.5x, or 50%.
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 to 225%
Source 1
This Pokemon's Attack is 1.5x, but it can only select the first move it executes.
Source 2
Hope this helps.
The Attack stat increase of Gorilla Tactics is 1.5x, mimicking the Attack stat increase of a Choice Band. This is one of the reasons behind why Galarian Darmanitan is banned to Ubers in competitve battling due to getting either a 1.5x Attack and Speed increase by holding a Choice Scarf and having the ability Gorilla Tactics, or by having a major Attack increase by having both a Choice Band and having Gorilla Tactics as its ability
Source
