This is a good team, though I'd be wary of Darmanitan being able to Flare blitz Frosslass, Yanmega, and Roserade, as well as EQ-ing Arcanine w/Earthquake and KOing Scrafty with superpower. Blastoise's would be the only one on your team to reliably stop him. The same goes for a Scarfed Fire Punch/Earthquake/Superpower Flygon. You may want to consider consider taking out your Roserade and putting in Zapdos/Raikou for faster Specs, and Zapados can take a Superpower from D-tan, and roost it off afterwards.