Q. What ways can a Pokémon get rid of an attached "Imprison" marker or "Shock-wave" marker?
A. Evolving, devolving, leveling up (i.e. LV.X), leaving play, and Tropius' "Tropical Heal" Poké-POWER are currently the only ways to get rid of an Imprison or Shock-wave Marker. Retreating or benching does NOT get rid of the marker. (May 31, 2007 PUI Rules Team)
* Imprison & Shock-wave Markers are special markers that were introduced in EX: Dragon Frontiers and will be included in theme decks for that expansion instead of the regular Burned and Poisoned Special Condition markers. After one these markers has been attached to a Pokémon, they are removed ONLY when the Pokémon evolves or devolves. Pre-existing cards such as Double Full Heal or Heal Energy do not remove these new markers an effect would specifically have to mention Imprison or Shock-wave markers for that effect to remove these markers. (EX: Dragon Frontiers FAQ; Oct 26, 2006 PUI Rules Team)