Pokemon Scarlet and Violet's Terastallization Could be Problematic With Some Abilities and Moves

gamerant.com:

Pokemon Scarlet and Violet's third trailer came with an in-depth commentary about the Paldea region, which shed some light on several mysteries surrounding Gen 9 until recently. Three new Pokemon were revealed in Paldean Wooper, Fidough, and Cetitan, and The Pokemon Company also showcased the new battle gimmick for Pokemon Scarlet andViolet. This mechanic is called Terastallization, which allows trainers to use a special item to change their Pokemon's type to a corresponding Tera type.

The latent Tera type can be any of the standing 18 Pokemon types in the series. Pokemon Scarlet andViolet's emphasis on Terastallization is great for team variety and versatility while battling, as trainers can Terastallize their Pokemon for offensive or defensive purposes, strategically changing their type on the spot. However, there are some instances where the Terastal phenomenon can cause problems due to any Pokemon being allowed to have any type. The main culprits are Abilities or moves that have to do with Pokemon types to any degree.

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One of the most interesting cases for the Terastal phenomenon is probably Shedinja, the only Pokemon to have an Ability called Wonder Guard that makes it immune to non-supereffective damage. Shedinja's gimmick is being a Ghost/Bug Pokemon with only 1 HP, meaning it is immune to 13 types out of 18, but the remaining types will one-shot it if they hit. Via Terastallization, a Shedinja can change its type to make it impossible for opponents to damage it with certain moves.

An item called Air Balloon makes its user immune to Ground-type moves at the cost of being removed when the Pokemon is hit by any other move. If Shedinja and Air