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

Bowed Whip

Choose 1 of your opponent's Pokémon. This attack does 30 damage to that Pokémon. (Don't apply Weakness and Resistance for Benched Pokémon.) Flip a coin. If heads, discard an Energy card attached to that Pokémon.

Deep Poison50+

If the Defending Pokémon is Poisoned, this attack does 50 damage plus 30 more damage.