No bad, but if you want to use your Roserade for capturing Legendaries, use stun spore. Stun spore doesn't wear off like sleep powder does. You could accidentally poison the legendary pokmon when it wakes up (via sludge bomb) and kill it when it has low health. Got that from experience. Then you'd have to battle the E4 and champ just to get another chance to catch the specific Legendary again.