I think the different HPs could work, but it might be better if one of the forms has a healing move so that you won't be stuck with too many damage counters to go into Attack Deoxys.
Defense form has DNA Recovery.
The only thing that sticks out to me with the set, is attack deoxys. 4 for 100 is not very good, especially with discarding all of them, on a 40 HP Body. It's too likely to get knocked out for little payback. I might make it (P)(P)(P) for 80 or (P)(P) for 60 or so. Maybe make it 50 HP so it can actually take a smaller hit.
Other than that, just minor things. I feel Speed's attack should just be (P), since it''s all about...well, speed. Normal Forme might be able to get away with having Psychic's base power be 20 or 30.
Other than that, it looks as solid as a Deoxys set will look.