For a move to be passed on, it must be on the father's moveset, not the mother (unless it's a move in the original Pokemon leveling skillset, it will have to be on both parents). Tutor moves won't pass down, so i don't know how you can get a Dark Pulse Misdreavus as it's not a TM in Gen V.
So what you get from a Cofagrigus with Curse, Will-o, Shadow Ball, Power Split and Hex, would be a Misdreavus with Psywave/Curse/ WIll-o-Wisp/ Shadow ball, and if your Misdreavus knows Pain Split too then that will be passed down and erase Psywave.
I'm going to search a way so that you can have the moves you want and come back later, but i'm pretty sure you can't get Dark Pulse yet until a move tutor, sorry.