With Xmen days of futures past releasing more and more trailers. It seems to be creating more questions than answers. For instance how is Beast in his normal human form again? Well it seem that after the events of Xmen First Class Beast played by Nicholas Hoult, has seemed to actually create the serum which hides his physical mutation. Although it doesn't answer how the hell Beast is all blued up and attacking Magneto.
Well, it seems that Beast took a page out of The Hulks playbook. That's right, when Beast is in a calm and collected state he appears as the lovable, shy genius. But when he gets worked up such as intense anger, experience large amounts of frustration he transforms into the blue hulk-like man beast. Increasing his strength, reflexes and speed. While in his original human form he does not exhibit any superhuman strength or durability, which is seen when Wolverine was able to force a door open with Hank McCoy exerting his strength on the other side. And again when Wolverine hits him in the face, which knocks the young scientist off his feet.
So there you go, explaining what to expect in Xmen and also answering the questions that need answers.