I like this set for Dusknoir:
Substitute
Will-O-Wisp
Focus Punch
Pain Split/Shadow Punch
I like Subpunchers, so that's why I like those two moves, Will-O-Wisp helps him survive for longer, and his Sub becomes very hard to break when they are burnt. :P
Pain Split helps you keep your health up, which is handy because you are using Substitute.. Shadow Claw is just here as an alterntive attack.
I realise he can't do much but stall against Ghost-type pokemon, but he's good at stalling anyway.
For EV's, I would put 252 in defence, 128 in special defence and 128 in attack.