Terastallization

Introduction

Terastallizing (aka Tera for simplicity) is a mechanic introduced in Pokémon Scarlet and Violet (Generation IX). In battle, when the trainer decides, it allows you to change a Pokémon’s type for the rest of the battle.

• Has to be activated by the trainer during the battle.
• You can only Tera one Pokémon once per battle.
• If you switch your Pokémon out, it keeps the Tera type when it comes back.
• Terastallizing cannot be undone.

In VGC.tools, we represent the Tera type with a special crystal-style badge, for example:

Before continuing, be sure to understand first how the types work in Pokémon. If you haven't done it yet, check the Types Guide.

Defense

Defensively, a Terastallized Pokémon is only that one type. Weaknesses and resistances are recalculated from the Tera type alone, which can remove weaknesses or add new ones depending on your choice. For instance let's take the same Terrakion from the Types Guide a Rock / Fighting pokemon.

We saw that for moves of type Fairy like Dazzling Gleam it would receive super effective damage (×2). Because Fighting is weak to it (x2) and Rock doesn't resist it (×1). So x2 * x1 = x2.

If we gave our Terrakion the Tera type Dark and activate it during the battle, then now it would be effectively only a Fairy type pokemon. So then the damage would be x½ as Dark resists the Fairy type (x½). So x½ * x½ = x¼.

Offense

Offensively, the Pokémon gets same-type attack bonus (STAB) for moves that match its Tera type. So you can gain STAB on a type you didn’t have before, or keep it on a type you already had.

When the Tera type is the same as one of the Pokémon’s original types, moves of that type get an extra boost (often called “same-type Tera” or “double STAB”). Just you need to know that the total STAB damage would be x2, instead of the usual x1.5 (not on top of the normal STAB).

The Stellar type is a special type. It would still give you the double STAB for the original types of your pokemon, but only once per battle. It would also give you a x1.2 to all your other moves, also only once per battle.

Recomendations

Choosing the right Tera type can make a big difference in your team's performance on VGC. Here there are some tips to have in mind when choosing the Tera type for your team.

• Choosing a defensive Tera is usually a better choice except for very specific cases.
• Gaining imunity from a Tera is very powerful, for instance trainers often use the tera Ghost to be immune to moves like Fake Out .
• Saving your Tera for the right moment is crucial to win most of your games, baiting your opponent to use it is a good strategy.