First off, get rid of both Charizards. Infernape is much better. You should definetely add a water type to your team. Due to the fraility of your team, Swampert is a good option. If you still want the flying coverage, then staraptor could be good, or togekiss. Your froslass is an attacking set, which isn't the best for it. A good special attacking Pokemon would work here. Luxaray isn't very good, but if you intend on keeping it then do so. You should take away everything but crunch, really. Give Luxaray more Physical moves.
Now, on to the items. On luxaray Use a choice band or scarf. Band increases his power to a great extent, while scarf will take care of his low speed. Infernape should use life orb. Swampert should have leftovers to further help its bulk, and Staraptor can use a choice band to really hit hard. Mewtwo should use a life orb because of its great power and good coverage.