Why the hell would you use ground gem?
If you aren't using leftovers you should probably try yache or passho berry depending on whatever the common UU leads are.
You should probably go 252HP/252Atk if you're running an offensive set, more HP is more useful unless you run pain split/eviolite (which obviously you can't do with donphan).
Ice Shard is better, you need the priority to get a lot of sashers after an EQ/things that are going to 2HKO and outspeed your shit (so you can revenge kill next turn without having to worry about the sash)

For alomomola it looks fine, however I would replace waterfall for either aqua jet (priority to finish things off, you won't be doing much damage with waterfall and you're slow anyways) or scald (burn for steel/poison-types, though you'll do less damage)

I dunno what to do with bisharp, I haven't used or gone against it enough.

Taunt would be more useful on a CM set.
I'd say lose HP fighting for either energy ball or HP fire/ground since HP fighting just doesn't cut it most of the time (but again, I don't really play UU so I don't know the common mismagius threats). If you're okay with just perfect coverage run sub for when you force a switch.

>>7693447
Thanks for the feedback, Scald completely slipped my mind on loma and I might as well go for the burn chance.

I see what you mean about Taunt, and you made a good case for Substitute which I wasn't so sure about before, I'll probably go with that.

>>7693447
This, exactly. The only thing I have to add is that bishop isn't good. I love it, but it's never going to be good competitively. If you really want to use it, run a swords dance sucker punch set, or a focus sash metal burst set (which can be useful, but it's unreliable). Any fighting type that I can think of would have good offensive synergy with mismagius - which should either go offensive or defensive IMO. Run 252 speed evs and timid nature no matter what, as you absolutely have to outspeed as many things as possible with mismagius. Now, either run nasty plot or calm mind on mismagius, calm mind for a more defensive set. Don't bother with spDef evs on either set. substitute is probably more useful than taunt - though you can go with taunt if you want.

One thing that >>7693447 got wrong was the hidden power. HP fighting is your best bet, but it can be replaced with thunderbolt. You should slash thunderbolt in with hp fighting rather than taunt.