There are several different types of rare champions scattered all over Pandaria -- hozen, jinyu, mantid, mogu, saurok, yaungol and pandaren. But these champions aren't like any rares you've seen on Azeroth. Rather than allowing players to simply stand there and beat the stuffing out of them, these rares have unique abilities that require tactics and skill to counter. Are they impossible to beat? Absolutely not, once you've figured out how to counter their bag of tricks.
But you cannot simply stand and beat them up anymore. Movement is absolutely key, and so are stuns, interrupts, and other abilities that define a class. Rather than allowing you to just spam your main attack, you're forced to practice moving out of the way of attacks, which are clearly defined on the ground. You can't let them cast every spell, or you'll certainly die. And kiting is definitely helpful in most cases as well.