First off, nice job mate.
Since you're going for a more offensive Roserade, definitely go with Technician, especially since you have HP Fire. For its moveset, I guess Magical Leaf, Extrasensory, and Spikes/T. Spikes/Toxic. Unfortunately, you don't have access to Sludge Bomb on it, which is arguably Roserade's most vital move, but you can either wait to get the TM for it in-game or try your hand at breeding another amazing Roselia where you'll just replace one of the hazard moves for Sludge Bomb. If you wanna know how to do it, just check Etesian's Breeding Guide / Recommendable Sets