Terastal revealed as Pokémon Scarlet and Violet’s core battle mechanic

After a very slight tease in the original trailer, we finally have a name and mechanical description for Pokémon Scarlet and Violet’s new battle gimmick—Terastal. 

The crystal-like Pokémon are unlike any battle mechanic that has been used in the series before, in that they only provide one change while incorporating elements from previous mechanics. For example, it can only be used once per battle—when a Pokémon returns to a Poké Ball it ends—and its main purpose is to give a Pokémon a same-type attack bonus (STAB) for any typing without actually changing their type. 

When certain Pokémon Terastalizes, they can actually change types into something else, like Eevee becoming a Water or Grass-type on its own. These are special Tera types, and only a select number of Pokémon can do this, while the rest receive the previously mentioned boosts.

Pokémon with those special Tera types are more likely to be found in the game’s new style of raid too.

Not giving Pokémon a third typing through some additional system is something that will keep the core gameplay of the franchise from getting overly complicated by adding more layers to the type chart. Giving Pokémon access to stronger affinities to types for moves they can already use, however, will add an element that provides further depth to the battle system in a way that Mega Evolution, Z-Moves, and Dynamaxing have in the past—though perhaps in a new, more dynamic way.