I've been trying to figure this for a while. Anyone know? I've tried an Aron with Curse, Torterra(And Turtwig and Grotle.) with Curse, and Hippowdon with Curse. All the above mentioned Pokemon were Male and the shieldon I had was female. Any help is appreciated.

All but the Hippowdon should have worked.

Well, the only thing I could think of is that Shieldon doesn't have enough move slots to get Curse.

If you don't understand, I'll put it this way.

Shieldon comes with 2 moves naturally.

Male pokemon has 3 moves that can be passed down.

Shieldon only has 2 move slots left.

I'm not sure if that can happen but it has to me when I was breeding Dragon Dance onto Bagon. Either try to move Curse to the first slot or delete some moves with the Move Tutor.

Oops meant to say never mind. Finally got it. I got "Don't seem to get along well." as a gesture that they wouldn't breed. Not the case. *Slaps head several times.*

when a mommy shieldon and a daddy aron love eachother very much, a skarmory who works for arceus brings them a baby shieldon with curse, and that's the easiest way to breed a shieldon with curse =)