I haven't had much to do related to competitive Pokemon in a while, but I'll give it my best shot.
Magnezone: Hyper Beam may have very high power, but it has pretty bad offensive typing and the after effect is less than desirable. May I suggest Light Screen to accomodate for the many Physical attackers you have? If you're using the Light Screen suggestion, give it the Light Clay (or whatever that item is). If not, just use the Leftovers.
Ferrothorn: Explosion is kind of the same deal as Hyper Beam: high power but not that great. Maybe you want to try Stealth Rock for some extra hazards and to combat the inevitable Fire types that will come to sweep your team.
Skarmory: Perfect just the way it is. I appreciate seeing an offensive Skarmory for once. Give it the Leftovers to hold or something. Items were never my strong point.
Steelix: Pretty good, although you may want to change the Nature to Relaxed if possible.
Metagross: Is good, I can't think of anything to make it better.
Scizor: Pretty good, although I have a fear that it won't be fast enough. May I suggest the Choice Scarf to help? If you do choose the Scarf, remove Swords Dance and put in either U-turn or Slash. Slash can work in the place of X-Scissor if you need it to as well.
Like I said at the top, I'm out of practice. But hopefully this helps a little!