During your opponent's turn, if Skull Fossil would be Knocked Out by damage from an opponent's attack, flip a coin until you get tails. For each heads, put 1 damage counter on the Attacking Pokémon.
Flip a coin. If heads, choose 1 of the Defending Pokémon's attacks. That Pokémon can't use that attack during your opponent's next turn.Put 1 damage counter on the Defending Pokémon.