If Cacturne is your Active Pokémon and is damaged by an opponent's attack (even if Cacturne is Knocked Out), the Attacking Pokémon is now Poisoned.

Feint Attack

Choose 1 of your opponent's Pokémon. This attack does 40 damage to that Pokémon. This attack's damage isn't affected by Weakness, Resistance, Poké-Powers, Poké-Bodies or any other effects on that Pokémon.