its quite nice....
a quick comment...
your last one has the button/joystick holes mapped on, but not on the first 3.
maybe you would want to map those buttons, and see where the joystick hole come at.... hmmmm.... if the joystick hole comes right btw the legs of Akuma, you might want to shift your characters a little... (I won't want to hold Akuma's ..... to play street fighter... heee heee.....

)
as for looking for background, ask snaaake.. he did tons of artworks like yours... maybe he can help you out and give you some background images for you to start working with.
good luck.
