It's not relevant to Standard or Expanded, but it can occur in Legacy or Unlimited in PTCGO. Scenario: Active UL Smeargle is poisoned, blocking its use of Portrait. Benched Genesect EX has Grass energy attached. Benched Verizion EX has Verdant Wind. UL Shaymin in the hand. Action: Play UL Shaymin from the hand onto the bench and use Celebration Wind. The online client allows you to move the Grass energy from Genesect EX to Smeargle and back to Genesect EX before clicking "Done". While the Grass energy was attached to Smeargle, but the effect of Celebration Win was not finalized, Verdant Wind removed the poison from Smeargle. I believe this is a bug because Celebration Wind is a one-time effect and in this case was used to move zero energy and Smeargle should remain poisoned. The client should not apply Verdant Wind until the "Done" button is clicked.