You have to clear and render the enemy to make it look like it is moving(look and try to understand the code instead of just backpacking everything. You can try and see the difference between the 3D Stage(with the "set color effect to 0" in the stage)and the 2D Stage(without the " set color effect to 0" in the stage) and see which one is better.
Owl by me(and it is a idea). The owl is about 20 wide and long as a reference. Who is making the collision engine?