The moon makes everything happen. That's the first thing you need to know. Everything supernatural in this world is chosen and set into motion by the Man in the Moon -- except for God and Jesus and Allah and all the other religious figures, which are never mentioned here and, for the sake of this narrative, simply don't exist. In their places are Santa Claus (the voice of Alec Baldwin), The Easter Bunny (Hugh Jackman), The Tooth Fairy (Isla Fisher), Sandman (a silent little gnome who creates golden dust storms of drowsiness and subsequent sweet dreams) and fledgling "guardian" Jack Frost (Chris Pine), who has yet to understand his own powers or believe in himself and is, therefore, invisible and not really a guardian yet. You'd think he'd never seen a kid's movie before; if there's one thing you're not allowed to be in a film aimed at the elementary school demographic it's someone who doesn't believe in himself. It's law.
The guardians, all four and a half of them, have the same job, to make their respective holidays and special events happen and, more importantly for their own job security, to make sure kids maintain their belief in the guardians. They also have complicated personas. The Easter Bunny is a huge, aggressive, Australian thing, mistaken for a kangaroo at least once, a Crocodile Dundee-meets-Donnie Darko lepus creature and somewhat stressed-out CEO of egg-dyeing. The Tooth Fairy is semi-retired, choosing instead to send thousands of tiny little employees out each night in her stead, dispensing money for teeth and banking children's dreams. See, your dreams are stored in your teeth which are, in turn, collected, arranged, cataloged and archived in personalized decorative tooth safes. She's more of a delegator in a feathered outfit you might have seen 1979 wearing to the roller-disco. Santa Claus is a giant Russian taskmaster with a Sons of Anarchy beard, hilarious elves and yetis as his personal slaves and "NAUGHTY" and "NICE" tattooed on his forearms, not unlike a lot of men you would find in any urban leather bar. And Jack Frost, as I mentioned, has no defined purpose. Yet.
Meanwhile, the film's purpose, it seems, is to prep children for their own inevitable disappointment with life as they grow older and realize that myths are just that, nice stories your parents told you to make everything in the world seem magical. But in the meantime the film's other job is to confuse its audience and dazzle them with swooping, soaring, adventure-spectacle so that too many questions don't get in the way of the "believe in yourself" thing and the other belief-based message of happiness through obedient, unquestioning assurance in stuff outside of yourself that isn't real at all. Oh, wait, except for the Boogeyman (Jude Law). He's real. Except you can also make him not real by not believing in him. Except he's still real and all you did was keep him at bay. Something like that. It's a contradictory exercise in discerning just what children are supposed to buy as solid and what they're supposed to wish away. Good thing it's fun to watch.
And while we're weighing what's real and what's not, did the movie just tell us [note: you might consider the next bit of information a spoiler if you think that a brand new origin story for longtime childhood fantasy figures can be wrecked with advance plot information at all] that Jack Frost, whose main superpower seems to be creating icy patterns on windows, drowned as a child? He's dead? And that's what made the moon pick him to make it snow? Sure, whatever. There isn't enough death depicted in kid's movies and not enough moon-based theology. And it pads this otherwise sort of pointless -- yes still entertaining swirl of strange -- with extra weirdness details. Points for that.