What happens when a Terastallized Flying-type Pokémon uses Roost?

Question

Would it be typeless?

Comments

https://pokemondb.net/pokebase/132324/what-would-happen-if-a-pure-flying-type-pokemon-used-roost#q132324
Does this count as a dupe?

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i thought tera pokemon couldn't have their types manipulated though, like tera electric double shock doesn't remove the electric for example

Answer 1

Most pure Flying types will become typeless for the rest of the turn. In essence, this means that all attacks will be neutrally effective against it. However, Terastallized Pokemon are unable to have their type changed in any way -- this includes modifications from moves such as Roost.

Terastal phenomenon (Bulbapedia)