If you guessed that the problem is that only the bad guy is a person of color, then you would be correct! This trope is so tired-so often the only people who are of color in a movie or a book are the characters that we're supposed to hate and when these images are used over and over again, the message that gets internalized is that Black people - or any other people of color - are evil. Now, I get it, "darkness" is inherently scary; people are naturally afraid of shadows, you say. To this I say that it is not exactly "darkness" that people are afraid of, but rather the unknown. There is a potential for violence that is scary, because it is unseen, but I would argue that this is more a product of our culture, than of darkness, itself. If darkness, itself, was so scary, then blind people would be forever paralyzed by fear, but that is not the case.
It almost seems that the makers of this movie have gone out of their to enforce the idea of whiteness being always the good guy, because there are so many obvious choices for characters of color. This is an animated movie, as such the creators are not bound by normal laws of nature, meaning the animators can create a character to look however they want. They don't even have to follow normal skin colors - why not make all of the tooth fairy green and blue and yellow? Why not make the elves red? I can see why Jack Frost would need to be White - he is, after all the maker of frost, which is a white substance, but I do not see the need for any of the other characters. I guess you could say that Santa Claus should be White, as that is how he is traditionally seen, and yet it is not unheard of to have a Santa of color.
(Look! One quick search using Google images brings up this lovely Black Santa candle holder!)
So saying that you need Jack Frost and Santa Claus to be White, which is not what I am saying, you still have the Tooth Fairy and the Sandman. These two characters do not have a standard representation and so they could easily be any race that the creator chooses. In fact, the animators were pretty creative in making the tooth fairy birdlike, so what I want to know is why did they stop drawing her colored feathers? She is covered in blue, green, and yellow feathers and yet when it comes to the skin on her hands and face, she is White. Frankly, I don't think that even makes sense. And then there's the Sandman, who is White with a golden glow. The elves also are all White, at least as far as I can tell from the previews. I don't like the idea of only the helpers being the people of color, but it'd be a step up from nothing.
It is racist to categorize White as good and Black as bad. If you are going to have a Black character be the bad guy, then you need to have at least one good guy be of color too. In this day and age, I feel like we as a society should be above these simplistic characterizations, but obviously we are not. We need to add more diversity to our pop culture and it needs to start with children's programming. The point was illustrated way back in 1954 with the Clark doll experiment. Kids were presented with two dolls - one White and the other Brown - and were asked which one was "nicer" and which one they would rather play with. The White doll won back then and it won again in 2006. If we do not want there to be internalized racism in our children and for White supremacy to still rule, then we must start with the images that we show our children. Would it have killed the makers of The Rise of The Guardians to have included a Black, Brown, Red, or Yellow guardian? No, of course not. Would it have been one more step towards a more equal and loving society? As simple as it sounds, yes.
(Look! It's a Black Tooth Fairy doll!)