There are lots of ways to do it. It depends a lot on how much flexibility you need to animate the various stages. If they are all pretty similar, you might be able to do it with one skeleton. Have you seen the
vine example project? You can customize the look quite a bit while still using the same rigging. If you need lots of different detail for the stages, you could consider skin bones to keep it a single skeleton or use a separate skeleton per stage. Note you can have multiple skeletons in the same Spine project.
One benefit of using a single skeleton is that you can use animations to transition between the stages. With a separate skeleton, at some point in your app you'll need to stop drawing the old stage and begin drawing the new one.