Responding to the OP - you should be able to animate a more complex shape - merged and grouped. What you cannot animate is sub-object features (e.g. control points) and unsupported effects.

Try these steps:

New animation
Create complex shape
Select all and group (if necessary)
Name object
Copy frame
Adjust scale, colour, rotation on copied frame
Repeat "copy frame and adjust" ad nausea
Play animation

My guess is that somehow the name is lost between frames of your animation - hence the jumping. If you plan your animation and only copy frames then the tweening of scale, rotation and colour should all work.