Q. What happens if I play ATM-Ice but the opponent doesn't have any trainer cards in play? A. If you cannot discard any of the opponent's trainers, you do not get the added protection benefit of the attack. You can still use the attack when they have no trainers in play; it just doesn't have any effect. (Jun 10, 2004 PUI Rules Team) Isn't it illegal to play a traner card for no effect? I'm going to guess that ATM-Ice (in that scenario) does not fall into that category, but I'm not sure.