uuuuuhhhh isnt that spam or something?
I guess. But is it wise to keep shadow sneak?
Can't someone put a stop to this non sense
Any Moderators around here?
And about Shadow Sneak; if you want to use it, bring DP with it. Since ghosts are primarily special attackers in OU, burn won't completely hinder them, and with DP as your only offensive move, they simply wall you/set up in your face and sweep your team (Misdreavus!). If it's a Gengar, it can just slaughter you too; with no Sp. Def EVs, Dusknoir's a sitting duck against it. The other common ghost, Misdreavus, which almost always has Leftovers, should be able to take quite a few SS'. So, I honestly don't see the point in running SS, unless you're dead set on it.
Rather, I highly recommend Pain Split as your last move, instead of SS. This is Dusknoir's only recovery move; and it actually has some uses. You can do moderate damage at first, without being forced to use another Dynamic Punch, while giving Dusknoir longevity by recovering his HP. Combined with Confusion and Burn damage, this should be doing as much as two Dynamic Punch's (and most likely, quite a bit more damage, since this type of Dusknoir isn't focusing on Atk EVs).
So, what I'm recommending as Dusknoir set is:
Dusknoir @ Leftovers
Gravity (lol obviously)
Will-O-Wisp (mandatory for stopping physical attackers, if you don't want your Dusknoir slaughtered!)
Rock Head isn't used in OU, period. :P Donphan doesn't have that ability, btw. You're thinking of the even more useless Sturdy.
Much more notable than Relicanth is the fact Aggron got Head Smash, thanks to HGSS. Head Smash coming off of 478 Atk (thanks to CB, ofcourse) is no joke. That's 7 points higher than Rampardos' normal attack stat. Combine that with Aggron's massively higher defense, and list of useful resists, (and ofcourse, the Rock Head Rampardos doesn't even have) makes him UU's juggernaut.
... Ofcourse, his use can be limited depending on the foe's team. One STAB Fighting or Ground move, and he's probably downed.
I was saying Double Edge being useless though, not Rock Head. :P