Same-Type Attack Bonus

[Abrien Sliver]

Same-Type Attack Bonus, or STAB for short. Some of you may or may not know what it is even though you probably use it, so to remedy that I'll tell most all of you what it is.

Same-type attack bonus, commonly abbreviated as STAB, is a 50% boost to an attack's power when the attack's type is the same as one of the types of the Pokémon using the attack. For instance, if a Blastoise were to use Surf, Surf's power would be increased by 50% since both Blastoise and Surf are Water-type. If Blastoise were to use Ice Beam however, it would receive no such bonus since Blastoise is not Ice-type. A Lapras, on the other hand, would receive the same-type attack bonus when using either Surf or Ice Beam since Lapras is both Ice-type and Water-type.

Hidden Power does receive same-type attack bonus. A Fire-type Pokémon will receive same-type attack bonus when using a Fire-type Hidden Power. Although Hidden Power is Normal-type in the game's data, a Normal-type Hidden Power is not really obtainable. Because of this, a Normal-type Pokémon will never receive same-type attack bonus when using Hidden Power.

Same-type attack bonus does not apply to moves that do a set amount of damage and do not use the normal damage formula, such as Dragon Rage and Seismic Toss.

Contrary to some of Nintendo's official guides, Normal-type Pokémon do in fact receive the same-type attack bonus when using Normal-type attacks, and same-type attack bonus is not reduced for a Pokémon with two types  

[Nadian]

The only thing I'll add is to mention, for those curious about how it actually works, STAB is really an increase of 50% in the damage dealt. However, this is close enough to the attack power increasing by 50% that it's a very worthwhile way to look at it that way. At best, this distinction only increases the amount of damage dealt by 1. sweatdrop

(Well, could also be an increase by 2 if it's super effective, or 4 if it's double super effective.)