It is now well-established (hopefully) that if an attack calls for the discard of energy from the Attacking Pokemon, that discard is mandatory. My question is, if such an attack is declared and the player cannot perform the discard, is it considered an illegal action, or does the attack do nothing? If it's considered an illegal action, the action is rolled back and the player may either declare a legal attack or pass. If the attack does nothing, it's still considered an attack and the player's turn ends (just like flipping tails on a flip attack). Which is correct?