Alright, so I just found out I have the Masuda Deoxys (the one with Nasty Plot) on my Diamond game, so here's a moveset for that:
I chose Speed Forme because Normal Forme and Attack Forme have garbage defenses so they can't set up, and Defense Forme plays a better role at Toxicking, Spike-setting, etc. Speed Forme has decent defenses, so it can set up and fire off nuclear-powered attacks after a Nasty Plot.
Deoxys-S @ Leftovers
EVs: 252 SpA / 252 HP / 4 Spe
-Ice Beam/Recover/Magic Coat
So here it is. Nasty Plot was the basis of this set, allowing Deoxys to set up. The EVs might seem strange, and indeed, they are, but they are to make sure it has enough bulk to set up a Nasty Plot. I really don't like using a Focus Sash set, as priority is all over the place in Ubers and Talonflame's everywhere in OU. Psychic forgoes the ability to wreck Chansey and Blissey for more power, so if that's what you like then you should probably choose it. Ice Beam can be used for coverage in tandem with Thunderbolt for the classic BoltBeam combo, while Recover is just useful as a move. Magic Coat can act as a surprise for those people who try to status you.