Terastallization is a battle mechanic introduced in Pokémon Scarlet and Pokémon Violet. A Pokémon can Terastallize once per battle under the format’s rules, taking on its Tera Type for type-based interactions. This can change defensive weaknesses and alter which moves receive STAB-related benefits. The exact offensive behavior depends on whether the Tera Type matches one of the Pokémon’s original types and on the game’s mechanics. Terastallization adds prediction because an opponent may change typing to resist an expected move or strengthen an attack. It is specific to Scarlet and Violet formats, so it does not apply to most older games.
