Just want to say that I love the team and the way you've written this. However there is one small part of your opening strategy that seems a bit shaky to me:
Ability: Natural Cure
EVs: 24 HP / 232 Spd / 252 SpAtk
Timid nature (+Spd, - Atk)
- Leaf Storm
- HP Fire
- Sleep Powder
- Spikes/ Toxic Spikes
Top ten leads are Gyarados, Hippowdon, Salamence, Gengar, Tyranitar, Bronzong, Weavile, Swampert, Infernape and Abomasnow. Roserade sleep powders Gyara, Mence (with 300 Speed), Bronzong, Gengar and Abomasnow. It leaf storms Hippowdon, Tyranitar and Swampert. The only 2 that force a guaranteed switch are Weavile and Infernape.
If I were you, I really wouldn't want to risk losing your lead Pokemon so cheaply to a Pokemon that literally preys on frail Pokes like Roserade that are afraid to take it on. If you do encounter CB Weavile at the start of the match, not only will you be losing your Roserade but in all likeliness Gengar too at some later point. This would automatically leave your team extremely vulnerable. I have to agree with Al and suggest Focus Sash on Roserade. It doesn't really have a use for Lefties, but with Focus Sash you can actually try and put Weavile to sleep before it can kill you (and lol if it tries to SD), as well as get a second chance against slower Pokes, rather than risk switching.
Also, I think Spikes+Leaf Storm is technically illegal, but not on Shoddy obviously.