This is generally good.
I really like the color composition and the X2, X3 and X4 drawings are great.
The unarmored and X1 drawings are... strange...
Firstly, in the unarmored drawing, I can see what may be a penis. I do not want that.
X also has a really long back and neck and his smile... Eah....
X's face in the X1 drawing makes him look like a different character than the other drawings.
His hand and the angle of his thighs are also strange.