um your wrong you can have as many as you want (up too four) of each type its like unowns.
I stand corrected. My old age/recent return showing.
In any case, there is still little justification for Speed, which basically has Feint Attack for CC. Running 3-3-3 Of Normal/Attack/Defense is probably the best way to go. You might throw in 1 speed for when you really need a 0 retreat because you don't have a Moonlight Stadium available, but otherwise Speed is the worst of the 4.
Actually, if Psychic Boost's effect ends if Deoxys retreats, you could continually cycle out Deoxys Attack for Deoxys Speed, then switch in another benched Deoxys and have that change to Attack and use Psychic Boost at full power again. This is unnecessary if Moonlight Stadium is in play, but you might want to run Snowpoint instead. If the choice is between putting in Q to do the same thing with Normal, or putting in Deoxys Speed, I'd go with Speed, since Speed is a mediocre start where Q is a horrible one.
Azelf Lv. X for support unquestionably, and Mightyena to take care of Mewtwo Lv, X.
Other must haves: Nightly Maintenance, which can get back any of the Deoxys forms you want.
I think the real trick will be getting rid of Aerodactyl, whose Pokebody really hurts your Deck. Deoxys Speed can pick it off, but it takes 3 turns. One potential solution is Unown M, which can use Magnet to flip a coin and draw Aero in to be swifty destroys by Deoxys Attack. It is still a coin flip though, and it will subject Unown M to damage it really can't afford to take.
After IFDS you could use 2 Pokeblower + to bring Aerodactyl in.