What is STAB in Pokémon?

The move needs to match

A Water-type Pokémon using a Water-type damaging move normally receives STAB. The same Pokémon using an Ice-type coverage move does not receive it simply because Ice is associated with cold water. For a dual-type Pokémon, an attack matching either of its types can receive the bonus.

STAB and type effectiveness answer different questions. STAB compares the attacker with its move. Effectiveness compares that move with the defender. A move can receive STAB and still be resisted by its target.

Compare more than the printed power

Suppose two otherwise comparable attacks have base powers of 60 and 80. If the 60-power attack receives the ordinary 1.5 multiplier, its type bonus gives it a nominal power comparison of 90 before the other parts of damage calculation. That does not make it universally better: accuracy, physical or special category and the defending matchup can change the choice.

This is a useful habit when choosing a routine attack. A reliable same-type move often deserves a slot even when a coverage move has a slightly larger printed number. Then use coverage for targets your main attack struggles to hit.

The bonus has exceptions

Abilities and game-specific mechanics can modify the usual bonus. Terastallization in Scarlet and Violet has additional STAB rules, so the simple baseline is not a complete Tera damage calculator.

Status moves do not become stronger just because their type matches the user. An attack that deals fixed damage also needs its own rule checked. Keep this explanation to ordinary damaging moves, then read the move or mechanic’s specific details when you encounter an exception.

STAB is useful background knowledge, not a requirement to calculate every turn. In the story, start with a dependable same-type attack and learn which matchups call for a different option.