>>51255347Every individual pokemon has a Tera type. Usually, this will be one of its normal types, but it doesn't have to be. Once per battle, you can terastallize one of your pokemon, changing its type to be whatever its Tera type is (replacing both of its normal types).
IF the Tera type is the same as one of the pokemon's normal types, then it will get bonus STAB.
Unusual Tera types are more common in raids.
Not confirmed, but leaked by Khu: There will be an item that lets you change Tera type, and a move that will have the same type as the pokemon's Tera type, so it will always have STAB. Also, the increased STAB goes from 1.5x to 2x.
