Candidate: Elsa.

Intro: Elsa steps through double doors made of ice and looks around. She notices the opponent and says "I'm bringing winter to you."

Costume 1: The blue dress she forms out of nowhere (that still confuses me)

Costume 2: What she wears during her coronation.

Victory pose: Elsa turns away from the opponent, looking satisfied, then causes it to snow on the stage while humming.

Babality: Elsa waves her hands in a circle and forms a small snowman. She then sticks a carrot onto it's face.

Fatalities:

(Let it go) Elsa stamps on the floor, freezing it and the opponent's feet. While they struggle to move, she waves her arm upwards and a collection of ice shards shoot out of the floor, impaling the opponent.

(The snow queen) Elsa creates a blizzard after telling the opponent "the cold never bothered me anyway", hiding herself from them. While they look around in confusion, she conjures a large snow monster which then starts tearing apart the opponent.