Via 4chan's Pokemon board, a user uploaded an image of what appears to be Chespin's final evolution. Before you check out the image, take note that 1) this could very well be a fake, and 2) if it is not a fake, it's definitely a spoiler.
Chesnaught? Personally, I'm not a fan of the odd ankylosaurus-esque Pokemon, but it's interesting that on top of a high defense, it's also a fighting type.
Assuming the image is in fact real.