Do the others holydays mascots exist in this AU and if so are then human, monster, Boss monster or wizard?
Not all exist. The tooth fairy might. And also Baba Yaga. They aren’t mascots of anything but whatevs. Those two are probably Boss Monsters who purposely refuse to have children and/or are infertile and thus immortal. Same with Mrs. Claus. The reindeer and elves are probably monster populations that have spanned over several generations and secretly live on the North Pole in a secret village beyond the reach of humans. They assist Santa in his endeavors to help foster good will in humanity.