The only thing I've ever found to work really well on smoke is a bleach/water solution. That's what they use to clean it off glass and windows and walls. I've never had a Greek pony though - I do know it worked amazingly well on US ponies after baking soda, freezer storage, tons of washing, and toothpaste all failed miserably. (I have a crazy sensitive nose, though - I can smell smoke a mile away.) Giving them a good scrub in some water with a little bleach in it took the smoke right off the plastic.