Please read Commit comments.
- Managed to iron out the problems. Basically there used to be a conflict between the beginMove in Entity that I thought there was, since a prior edit you have made changed some part of it. However it's all good now. I modified the various beginMove methods you have overloaded so that it works for both of us. 
- Wrote a preliminary script, a draft of the stage1boss. It works right now, if you try it out, it should repeatedly attempt to bodyslam you. A word of warning - it attacks rather rapidly! You might lose if not prepared.
- As per your orders, I modified the MoveableEntity's continueMove function in order to allow velocity, rather than some constant you had declared before, to be factored into the calculation. Consequently everything all works out now.