Couple of points:
No Ice attacks will make it difficult to take out Dragons. Seriously consider replacing one of Latias' attacks with Ice Beam, at least when you reach 35 wins or so.
Each pokémon in BT has to have a different held item. No 3xLeftovers allowed. I'd give Crobat a Lum berry - protects vs a whole bunch of trouble, including Confusion and Attract.
Earthquake AND Brick Break on Slaking is a little redundant. Hyper Beam is better than Return for it as well.