I don't recommend that set. Dark has poor coverage only hitting Ghost and Psychic for super-effective damage and it's a one time shot. If you mispredict and Fling the wrong target you'll be stuck with three attacks for the rest of the match.
Also when it comes to Trick Room teams, you're catching the foe off guard so slowing down your Pokemon further doesn't help matters at all. Even when you get rid of the Iron Ball and Trick Room ends, you'll fail to outrun anything with a weak 176 Speed making it poor for sweeping. Best you can do is possibly tie Skarmory, Breloom, and Metagross with neutral nature and no speed investment.
I can't seem to recommend any other physical attacks, but Swords Dance is an option if you don't mind burning a turn of Trick Room to get a +2 boost for your other two attacks.