I KNEW i joined Team Rogue for a reason! We are of like minds! Already have aforemetioned Metagross deck. Should/will post soon. I was begining to think that i should just forget about Altaria, like you said for the very same reason. As I type this I'm still trying to figure out the best Gengar DP approach. Ampharos SW won't really guarentee a KO, though. If they know that when they play a supporter that they'll take a damage counter, AND know that Gengar is around, they should be smart enough to avoid it. Skuntank G also poisons me(unless I have Skuntank active that is) so I don't think that's the best solution.
Now we come to Dusky X. It's been suggested by 2 other people, so I'm most likely to use him, though I'm not exactly sure in what capacity other than to have him die and become a stadium for autodeath between turns. BTW, I'm running a 4-3-3-1 Gengar line.
Also, what Dusknoir should I run? I'm really leaning toward DP as well because I already have 2 copies. So unless i get overwhelming imput that says that SF is infinately better, i'll probably run that one.
The one nice thing i see about SF is that Shadow Command both helps me and slowly kills off Dusknoir, speeding up the process.