It's better than the all-out attacker in my experience. The two also play differently: one is a wall breaker, the other more of a sweeper.
[SET]
name: Stat drop-less attacker
move 1: Psyshock
move 2: Low Kick
move 3: Ice Beam
move 4: Extremespeed
item: Life Orb
nature: Naive / Rash
evs: 4 HP / 252 SpA / 252 Spe
Why this set deserves to be on site (also set comments)
No stat drops makes Deoxys-A a lot more threatening, because you cannot play around with resistances while it burns its stats. For example, while you do deal a ton of damage with Psycho Boost, your opponent can equally switch out to a Psychic resist (like Lugia) and then recover health as you are forced to switch out. Granted, Deoxys-A can still attack from the physical side after a Psycho Boost, but that too can be played around: going to Dialga on Psycho Boost and then Groudon on Superpower, for example, means Deoxys-A achieves nothing. Since Deoxys-A's switch-ins are so precious, each time something like this happens you have trouble.
Without stat drops, playing around is a lot riskier. You could still go to Dialga on Psyshock and then Groudon on Low Kick, but Deoxys-A is still threatening to OHKO with Ice Beam. Hazards take their toll and all you have as compensation is the Life Orb recoil - not good enough.
Low Kick is here because most Uber Pokemon are very heavy. You can't take out Chansey and Blissey in one hit anymore, but Psyshock 2HKOes both of them so no worries. If they have Thunder Wave then they can sacrifice themselves to paralyze Deoxys-A, but most Chansey seem to have Toxic, I haven't seen much if any Blissey. On the other hand, I have caught a few people attempting to switch in Giratina / Giratina-O on the Fighting move, smacking both hard with Psyshock and (in Giratina's case) threatening Ice beam ...
[Additional Comments]
Alternative EV spreads
Alternative move choices (Grass Knot, Thunder / Thunderbolt, Shadow Ball, HP Fire - pity Deoxys-A doesn't get Fire Blast / Flamethrower).
[Checks and Counters]
The four moves listed above are walled by Forretress, but aside from that ... it's Deoxys-A. Depending on its coverage choices it 2HKOes everything in the game. So basically just figure out its moveset (if you can) and check it accordingly. Worst case scenario, bring in a faster Scarfer or priority move and kill it.
[SET]
name: Stat drop-less attacker
move 1: Psyshock
move 2: Low Kick
move 3: Ice Beam
move 4: Extremespeed
item: Life Orb
nature: Naive / Rash
evs: 4 HP / 252 SpA / 252 Spe
Why this set deserves to be on site (also set comments)
No stat drops makes Deoxys-A a lot more threatening, because you cannot play around with resistances while it burns its stats. For example, while you do deal a ton of damage with Psycho Boost, your opponent can equally switch out to a Psychic resist (like Lugia) and then recover health as you are forced to switch out. Granted, Deoxys-A can still attack from the physical side after a Psycho Boost, but that too can be played around: going to Dialga on Psycho Boost and then Groudon on Superpower, for example, means Deoxys-A achieves nothing. Since Deoxys-A's switch-ins are so precious, each time something like this happens you have trouble.
Without stat drops, playing around is a lot riskier. You could still go to Dialga on Psyshock and then Groudon on Low Kick, but Deoxys-A is still threatening to OHKO with Ice Beam. Hazards take their toll and all you have as compensation is the Life Orb recoil - not good enough.
Low Kick is here because most Uber Pokemon are very heavy. You can't take out Chansey and Blissey in one hit anymore, but Psyshock 2HKOes both of them so no worries. If they have Thunder Wave then they can sacrifice themselves to paralyze Deoxys-A, but most Chansey seem to have Toxic, I haven't seen much if any Blissey. On the other hand, I have caught a few people attempting to switch in Giratina / Giratina-O on the Fighting move, smacking both hard with Psyshock and (in Giratina's case) threatening Ice beam ...
[Additional Comments]
Alternative EV spreads
Alternative move choices (Grass Knot, Thunder / Thunderbolt, Shadow Ball, HP Fire - pity Deoxys-A doesn't get Fire Blast / Flamethrower).
[Checks and Counters]
The four moves listed above are walled by Forretress, but aside from that ... it's Deoxys-A. Depending on its coverage choices it 2HKOes everything in the game. So basically just figure out its moveset (if you can) and check it accordingly. Worst case scenario, bring in a faster Scarfer or priority move and kill it.