Great team super pascal but I see a huge kingdra weakness in the team. As soon as arceus is gone or somewhat weakened (burned or just low on hp without boosts) it looks like kingdra with sub can clean up the whole team. Ferrothorn cant touch it because of sub, palkia and dialga say hi to dragon pulse and draco meteor and hydropump in the rain is hitting mewtwo very hard.
LO kingdra's max sp atk draco meteor vs dialga = 282 - 333 (78.99% - 93.28%) guranteed ohko with rocks and a layer of spikes
LO kingdras max sp atk hydropump vs mewtwo = 366 - 432 (103.68% - 122.38%) really mewtwo's just screwed here in this case ._.
So in order to get rid of this problem i say that if we cant beat em join em. I think replacing kingdra with palkia should help cleaning up and since no one uses max speed kingdra the evs can be tweaked a bit to speed creep or you could just run max speed. Either that or you could replace toxic with power whip on ferrothorn (argh magic bounce and taunt alleviation too ) so that he doesnt just become dead weight when a super fast dragon that is a kingdra with decent offense tries killing him.