I used this set in 5th Gen.
Offensive Roserade
Roserade @ Life Orb
EVs: 4 HP / 252 SpA / 252 Spe
Nature: Modest (+SpA, -Atk)
Ability: Natural Cure
IVs: 0 Atk
- Leaf Storm
- Sludge Bomb
- Sleep Powder / Dazzling Gleam
- Rest
I added Dazzling Gleam for the hell of it but Leaf Storm does more damage to basically everything you're gonna be using Dazzling Gleam on from the top of my head.
Defensive Roserade
Roserade @ Black Sludge
EVs: 252 HP / 252 SpD / 4 Spe
Nature: Calm (+SpD, -SpA)
Ability: Natural Cure
IVs: 0 Atk
- Spikes
- Aromatherapy / Sleep Powder
- Synthesis / Sleep Powder
- Sludge Bomb
If your team is in dire need of a cleric, then use Aromatherapy. The reason I don't even slash Toxic Spikes is the amount of Pokemon in the OU metagame (since I believe you're talking about this tier) are basically immune to it (Rotom-Forms, Genies, Steel-types, Levitaters) or can absorb it (Mega-Venusaur). If you do want Toxic Spikes for whatever reason then feel free to add it but yeah.