Something wrong with her natural looks
There is something wrong with the way the director of the current X-Men movie handled Mystique's loss of powers. It is to my understanding that her original form is blue-skinned, not pink. Therefore, when she lost her powers, the only thing that could have changed within her was her morphing abilities.
To affirm my views, in X-Men 2, Nightcrawler asks Mystique why she doesn't change and pretend to be normal all the time. She answers, "Because we shouldn't have to." Or, something like that. This goes to show that she recognizes that her true form is blue-skinned.
In addition, in the first X-Men movie, after Wolverine punctures her in the stomach, she passes out, reverting back to what appears to be her true form: blue-skinned.
The serum she was injected with will only stop her powers of transformation. When she became pink / white-skinned, the serum not only neutrilized said powers, but transformed her from one race to another. Clearly, the parameters of the serum have gone way and beyond the original set of rules.
By the same token, Beast should not have been affected because his change was caused by chemical experimentation that altered his DNA. Not only his skin, but also his powerfully muscular features are a NATURAL state for him. If you try to "cancel" his powers, his NATURAL physique demands that he still looks like a beast, and still be as strong as a gorilla.
It is true that I did not graduate from M.I.T with a doctorate degree in rocket science. But, I can still make sense of what is supposed to be logical. And, in this case, logic is out of whack.