Interesting team here, though I think I have a few suggestions.
First is putting 252 HP 4 spatt and 252 speed on Latias. It works much better in my opinion. Also if you're planning for a sweep I suggest HP fire over Roar. you WILL be walled by steel types.
I would suggest changing Heatran's set since it's a little situational and a little bit gimmicky(I mean a little). But if it really works for you then keep it.
Volcarona is going to have a wonderful time once Tornadus and Rotom-w are down, specially in the sun, I understand Heatran can stop it but most Volcs carry HP ground just to destroy Heatran. So watch out for Volc in the sun. Back to what i said previously you might want to carry an air balloon set to make sure Volc doesn't destroy you or use specially defensive Heatran and roar Volc out before it can set up(volc can't OHKO without a boost from quiver dance).
that's all I really have to say :)