With the release of Pokémon Scarlet and Violet right around the corner, a new trailer recently dropped that revealed a bunch of information about what players can expect from the Paldea region. Apart from several new Pokémon being shown for the first time, one of the most notable of these new announcements was the introduction of the Terastal game mechanic.
Following in the footsteps of previous region-exclusive gimmicks like Mega Evolution, Z-Moves, and Gigantamax, the Terastal mechanic adds a fun and interesting twist to Pokémon battles, though some fans believe that Game Freak should be expanding more upon previous gimmicks rather than always adding new ones. While not every detail of how Terastal works has been released yet, the information that has been shown has raised one very important question. How is this going to affect the Pokémon Shedinja?
Having first appeared in the series' Third Generation, Shedinja is a unique Pokémon in that it only ever has one single Hit Point. However, this is countered by its Special Ability, called Wonder Guard. A Pokémon that has the Wonder Guard Ability becomes completely immune to any damaging moves that are not Super Effective against it.
The Wonder Guard Ability is typically balanced fairly well, as Shedinja's Ghost and Bug typing make it weak to several types, including Fire and Flying, which most players tend to have at least one of in their Pokémon Party. However, the current information available about the Terastal mechanic makes it seem like it could disturb Shedinja's balance.
As was shown in the recent trailer, the Terastal mechanic has the ability to temporarily change a Pokémon's typing once activated. Fans can see this in action with the Flying Pikachu, an early purchase bonus that has a long history in the series. The official Pokémon website states that "All Pokémon in the Paldea region are able to Terastallize," so it can be inferred that if Shedinja does make an appearance in Pokémon Scarlet and Violet, it would definitely be able to Terastallize.
Though it's currently unknown how long a Pokémon will remain Terastallized during a battle, if it lasts the entire battle like Mega Evolution or just a handle of turns like Gigantamaxing, this could be huge for Shedinja, even if it's just for a few turns. If, for example, Shedinja were able to temporarily transform into an Electric-type, it would then only have a single Super Effective weakness from the Ground-type. Further, there is a held item called Air Balloon that acts similarly to the ability Levitate, making any Pokémon holding it actually immune to Ground-types. Therefore, if a Terastallized Shedinja were able to keep its Wonder Guard Ability, it could become almost completely invulnerable with just a little amount of setup.
There are other ways around the Wonder Guard Ability, such as the status conditions Burn or Poison, which deal indirect damage to a target, or the held item Rocky Helmet, which does a small amount of damage back on any Pokémon that attacks its holder. However, there are many Pokémon fans who don't use status condition moves or special held items, particularly if they're not involved in the competitive scene. For many players, then, a Terastallized Shedinja might just be the closest thing there is to an unstoppable Pokémon.