dude, you only have one dragon move. use life orb for bulk. also, replace thunder punch with something else for better type coverage. note that max evs are 252 per stat/508 total. so, keeping in line with the current set, 52hp/252atk/200sp.def. natures good.
again with the item. also, milotic seems to be a wall, so try leftovers. your moveset is good, though maybe replace hydropump with water pulse, and another with lighscreen? evs are 200def./108sp.atk/200sp.def
gonna change moveset/item
-whatever you want
item:choice atk upper
meteor mash instead of reflect. metagross is a tank. like the speed reducing+quick claw
evs are 100hp/252atk/256def.
obviously a special tank. not much I can say, but evs are 100def./252sp.atk/156sp.def
slightly bulky, but focus sash still good idea. evs 252atk/252sp.def/4spd
no toxic, but someother move like u-turn to negate superpowers effects