Trades

Sadly, yes

The male snake has to learn it by TM in gen 4 then it has to be pokeshifted to gen 5 where it breeds with a female Deino to get a Deino with Dark Pulse.... lots of work. That would be awesome, I can wait Plus if you don't want to use your TM for Dark Pulse, you can trade it to me and I can use mine~

Don't worry about that. I'm prtty much retired from 4th gen, and if a Dark Pulse TM is going to be used for anything, I can't imagine a better argument than "It's the only way to get Dark Pulse on Hydreigon."

I'm kind of motivated to breed and raise a Deino with Dark Pulse myself. I'm probably going to get to work on a VGC team someday and this sounds like it's too good to pass up.