From Bulbapedia, the community-driven Pokémon encyclopedia.
The same-type attack bonus (Japanese: タイプ一致ボーナス coincident type bonus), abbreviated STAB, is a damage boost that is applied to moves used by a Pokémon of the same type.
In the core series games
If a Pokémon uses a damaging move that has the same type as one of that Pokémon's types, the move's damage is increased by ×1.5. If a Pokémon has the Ability Adaptability, the boost is ×2 instead.
This bonus has been present in all core series Pokémon games.
The type of the move when it is used is used to determine whether it receives the bonus, not its listed type. For example, if a Fire-type Pokémon uses Weather Ball during intense sunlight (so that the move becomes Fire-type), it will receive the bonus; however, if a pure Normal-type Pokémon uses Weather Ball during intense sunlight, it will not receive the bonus, despite Weather Ball being listed as a Normal-type move. Flying Press is a Fighting-type move, not a Flying-type move, despite using the type effectiveness of both types.
Pledge combination moves (two different moves from among Grass Pledge, Fire Pledge, or Water Pledge performed by the same team on the same turn) always receive the bonus, even if neither of the performers share a type with either half of the move combination (for example, a Silvally with Grass Pledge and a Smeargle with Water Pledge).
The same-type attack bonus is applied as part of the damage formula, so does not apply to damaging moves that do not use the damage formula to calculate damage. Likewise, damage that is not the direct result of a damaging move (such as poison damage, or the additional effect of Flame Burst) does not receive the same-type attack bonus.
Additionally, from Generation II onward, Struggle does not receive the same-type attack bonus. From Generation II to IV, Beat Up, Future Sight, and Doom Desire also do not receive the same-type attack bonus.
Pokémon that do not have a type do not get a bonus when using a move that does not have a type. For example, if a pure Fire-type Pokémon that used Burn Up (and so no longer has a type) uses Revelation Dance, Revelation Dance will not have a type, but does not receive the same-type attack bonus.
Shadow moves (which only exist in Pokémon Colosseum and XD) never receive the same-type attack bonus.
In the spin-off games
In the Mystery Dungeon games, STAB boosts damage by 50%.
In Pokémon GO, STAB boosts damage by 20% (25% prior to June 21, 2017).
In the manga
In the Pokémon Adventures manga
The concept of same-type attack bonus was mentioned by Ruby in Omega Alpha Adventure 3, noting how Zinnia used her Mega Salamence's Aerilate to give its Hyper Voice a power boost.
- Contrary to what some early strategy guides stated, Normal-type attacks can receive the same-type attack bonus.
- Protean and Libero change the Pokémon's type to match the move it is using, allowing it to always receive the same-type attack bonus.
- The Ability Normalize changes all of the Pokémon's moves to be Normal-type, allowing a Normal-type Pokémon to always receive the same-type attack bonus.
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