The basic premise of The Last Mimzy seems fairly standard for this list: a young boy and girl are stunned and delighted when their stuffed rabbit turns out to be more than a simple stuffed animal. Where Mimzy differs is the fact that it's not a magical being, but an artificially intelligent creation of future humans, sent back in time to return with DNA uncorrupted by widespread pollution. Also, it turns children into telekinetics and telepaths so it can communicate.
That's a heavy story for a young audience - even moreso when the plot is placed under a microscope. Mimzy's young master is needed to save the future, but the plan was never to prevent the pollution in the first place. So the children will be forced to watch humanity stumble, with or without superpowers.