Teal Mask starts with meeting Nila and Lae, two siblings and new friends/rivals from Kitakami. Nila and Lae study the legends/folktales of the land and tell you a story of three pokemon who once were saviors of Kitakami, as the protected the land from a malicious pokemon. So the people throw a festival in honor of the saviors. Ogerpon is first seen as an antagonistic pokemon disrupting the festival, but later you come to realize that it originated from Area Zero and is the reason behind the special Tera forms and has a close connection to Terapagos. As you find the saviors: Okidogi, Munkidori, and Fezandipiti to combat Ogerpon, you gain access to the special Tera forms.

Which include: The Saviors, Ogerpon, the Paldea Starters, Charizard, Pikachu, Greninja, and Decidueye. These forms don't change the appearance hardly but instead of the Tera hats, they are masks. Also these pokemon gain access to a name move similar to Tera Blast but stronger.

The types and Mask Forms are...
Okidogi- Fighting/Poison (Grass)
Munkidori- Fighting/Dark (Water)
Fezandipiti- Fighting/Psychic (Fire)
Ogerpon- Fairy/Dark (Ghost)
Charizard- (Dark)
Pikachu- (Fighting)
Greninja- (Poison)
Decidueye- (Steel)