If this Baby Pokémon is your Active Pokémon and your opponent tries to attack, your opponent flips a coin (before doing anything else required in order to use that attack). If tails, your opponent's turn ends without an attack.
The Defending Pokémon can't retreat during your opponent's next turn
The Defending Pokémon is now Poisoned. Put 2 damage counters on instead of 1 between turns