Discard a Fire Energy card attached to Shining Mewtwo or this attack does nothing. This attack does 40 damage plus 10 damage for each Energy attached to the Defending Pokémon.
If an attack does damage to Shining Mewtwo during your opponent's next turn (even if Shining Mewtwo is Knocked Out), flip a coin. If heads, prevent all damage done to Shining Mewtwo from that attack (any other effects of attacks still happen) and do 20 damage to the attacking Pokémon.
You can't have more than 1 Shining Mewtwo in your deck.