Same-type attack bonus, abbreviated to STAB, grants a 50% boost to the power of an attack that matches one of the types of the Pokémon that uses it. The result of this is a 50% increase in damage (this becomes 100% if the Pokémon has Adaptability).

Examples of STAB in action

A Smore using Leech Life increases the power of the move from 20 to 30, since both are Bug-type. Smore using Ember however, does not get the 50% special attack bonus, since it is not a Fire-type Pokémon.

Firoke, on the other hand, would receive the same-type attack bonus when using either Leech Life or Ember, since Firoke is a dual-type Bug- and Fire-type Pokémon.

Variable power moves

STAB is ineffectual on moves that do not use the normal damage formula (any move where the power is displayed as varied on its move page, such as Low Kick or Fling)

Variable type moves

A Pokémon only receives STAB on the current type of the move, not its listed type. For example, if the user's type matches their Hidden Power type, they do receive same-type attack bonus; however, since a Normal-type Hidden Power is not possible, a pure Normal-type, or a pure Fairy-type Pokémon cannot receive STAB for Hidden Power.