The Teal Mask is part 1 of Pokemon Scarlet & Violet's expansion pass: The Hidden Treasure of Area Zero, much like Gen 8's Isle of Armor was to Pokemon Sword/Shield. As Gen 9, many fans were expecting the Teal Mask to have stronger content - story, characters, etc - over Isle of Armor. Like every other DLC, Teal Mask has its pros and cons, but there are some things it does better than Isle of Armor.