Really nice! Cool style too. I wish we could see what the environment looked like around this style.
As for suggestions:
I'd animate the hat so that it only bounces with as much force as it looks like it should inherit, and only after a sudden change in direction of the thing that was holding it up. I think the animation of the hat in high speed looks okay. The one in medium speed looks a bit weird because the butt part of the elephant isn't even bouncing that forcefully but the hat is going way up.
You really did a great job with everything else though. I think it's why the hat particularly sticks out.
And nice work deforming the legs. It looks great.
What happened to this elephant? Why does he have a missing trunk and leg?
