Tried it out, but I couldn't get much mileage out of Screech. In most cases, just attacking outright was the best option. Screech seems good only if you don't know your opponent's Aggron counter or something.
Fair enough; but how does your Aggron fair against the likes of Donphan and Milotic (if running RP or CB of course).
I mentioned Substitute in AC because with LO Aggron would die way too quickly and be less effective because it limits the amount of times he can switch in on Swellow, for example. Substitute with something like Hard Stone would be possible, but than Aggron is too weak to kill off what he's supposed to, and there's the dilemma. I just prefer knowing that the opponents Milotic and Donphan are going to be eliminated. I guess I can change this to a Substitute + 3 attacks set if there's enough support for it, as they function pretty much the same, besides for much less survivability.
The problem is that the Rock Polish set doesn't OHKO these threats so he ends up being OHKOed instead.