How type effectiveness works: multipliers, dual types and STAB

Four possible results for one type

Every move has a type, and every Pokémon has one or two types. When a move hits, the game compares the move’s type with each of the target’s types using the type chart. Against a single type, a move does one of four things: 2× damage (super effective), 1× (normal), ½× (not very effective) or 0× (no effect). There are 18 types, so the chart has 324 matchups, but most of them are a plain 1×.

How two types stack

When the target has two types, the game multiplies the two results. That gives six possible values.

• 4×: weak on both types, such as Rock against Fire/Flying.
• 2×: weak on one type, neutral on the other.
• 1×: neutral on both, or weak on one and resistant on the other.
• ½×: resisted by one type, neutral on the other.
• ¼×: resisted by both, such as Grass against Fire/Flying.
• 0×: either type is immune, whatever the other one says.

Same-type attack bonus

A move gets a 1.5× bonus when its type matches one of the user’s types, called the same-type attack bonus or STAB. A Fire type using Flamethrower gets it; a Water type using Flamethrower does not. STAB multiplies with the type matchup, so a super-effective STAB move does 3× the damage of a neutral non-STAB move of the same power. That is why most Pokémon carry moves of their own types first.

Tera Types in Scarlet and Violet

Terastallizing changes a Pokémon’s defensive type to its single Tera Type for the rest of the battle, which can remove a 4× weakness or turn it into an immunity. On offense, the Pokémon keeps STAB on its original types and gains STAB on the Tera Type. If the Tera Type matches one of its original types, that STAB rises from 1.5× to 2×.

Where type matchups fit in damage

The type multiplier is one of several factors in the damage formula, alongside level, the move’s power, the Attack and Defense stats, a random factor, critical hits, weather and items. A 2× hit from a weak move can still do less than a resisted hit from a strong one, so matchups tell you what is favorable, not exactly how much damage you will deal.