Originally Posted by
Depression Moon
Are there any Majora's Mask characters in it?
No. But there is a
Majora's Mask DLC coming.
DLCs announced thus far:
Master Quest Pack.
Twilight Princess Pack.
Majora's Mask Pack.
Ganon/Boss Pack.
The
Master Quest pack is known to contain
Epona as a weapon for Link. Contains a story mode for Cia, Volga, and Wizzro, explaining how they met, and offering upgraded weapons and heart pieces/containers for them. Contains "Master Quest" mode, which allows you to play with a harder difficulty (including one where no hearts spawn on the map). There's a rumored new Adventure Mode pack as well, but no new characters are believed to be added.
I don't really see how we can get a
Majora's Mask pack without getting some characters from the game, though. Sure, we can maybe get Masks as another weapon for Link (adding in his Deku, Zora, and Goron transformations to his combos). But beyond that, you can't do a lot without bringing in some characters.