* Deoxys-A's offensive stats help ensure its potency in the metagame.
* Access to a powerful STAB move and good coverage options allows it to plow through many of the Pokemon that reside in the tier.
* Psychic Terrain boosts its viability further and makes it difficult to effectively revenge kill.
* Its virtually non-existent bulk leaves it easy to KO with almost any attack, especially priority attacks.
* It has a slight case of four-moveslot syndrome, meaning that it cannot simultaneously check everything it wants to check.
* With a pure Psychic typing, its STAB moves have noticeable power, but its coverage moves leave something to be desired.
name: All-out Attacker
move 1: Psycho Boost
move 2: Ice Beam / Knock Off / Pursuit
move 3: Superpower / Low Kick
move 4: Extreme Speed / Psychic
item: Life Orb
nature: Rash / Naive
evs: 4 Atk / 252 SpA / 252 Spe
* A Life Orb-boosted Psycho Boost is guaranteed to OHKO all non-specially defensive Primal Groudon variants, and Stealth Rock damage makes that margin of error even narrower.
* Ice Beam hits many Dragon- and Flying-types in the tier for super effective damage.
* Knock Off hits many opposing Psychic-types super effectively and cripples other item-reliant Pokemon.
* Pursuit is a unique option to deal unexpected damage to Pokemon that don't want to stay in and take an otherwise more powerful move.
* Superpower is a strong, consistent Fighting-type coverage move, but it comes at the expense of lowering Deoxys-A's Attack and Defense stats.
* Low Kick is another option with no stat drops, but it only hits the heavy Pokemon for full power and thus isn't as strong against the likes of Klefki and Magearna.
* Extreme Speed is a strong priority move for anything that needs to be quickly defeated.
* If used on a Psychic Terrain team, Deoxys-A can run Psychic over Extreme Speed in the final slot, as it is another powerful non-priority STAB move that doesn't induce a Special Attack drop.
* A Rash nature maximizes the power of Deoxys-A's special moves, most notably its hard-hitting Psycho Boost, and thanks to its frailty, its Special Defense is not too important.
* The given EV spread maximizes Deoxys-A's Special Attack and Speed to ensure the highest possible damage output from Psycho Boost, and some Attack investment helps add to the power of its physical moves.
* Life Orb adds to its damage output, and because any hit will most likely OHKO it, the recoil damage is not too hindering.
* Running a Naive nature makes Deoxys-A slightly weaker and causes it to fail to OHKO Giratina-O and non-defensive Arceus formes after Stealth Rock, but in exchange, it allows Deoxys-A to outspeed Choice Scarf Landorus-T and at worst Speed tie with opposing Deoxys-A.
* Focus Sash is an option to let Deoxys-A take a hit when at full HP, but it's not easy to keep intact, and Deoxys-A loses out on some significant power.
* Use Deoxys-A offensively, either as a sweeper or as a late-game cleaner.
* Let teammates take care of problematic Pokemon and weaken a few others, then send Deoxys out and KO the rest with the appropriate move.
* Even though Deoxys usually gets knocked out by any hit it takes, sending it out in weather or while entry hazards are up on your side of the field is not recommended, as Life Orb and passive damage will accumulate, and the Focus Sash will outright fail to achieve what it was meant to achieve.
* Focus Sash is often used in the lead role, as that is when there are no entry hazards on the field and weather damage is the least likely to occur.
* Deoxys-A does not really need any specific teammates, as it is strong enough to dish out plenty of damage on its own and frail enough to get KOed by anything. Thus, teammates should make it easier for Deoxys to achieve the former.
* If running Focus Sash, an entry hazard clearer such as Giratina is recommended, but Focus Sash variants are usually meant to be played as a lead anyway.
* Primal Groudon removes weather and absorbs burns and Thunder Waves directed at Deoxys. Mega Sableye also helps in bouncing back detrimental statuses.
* Strong Fire-types, like Ho-Oh or the aforementioned Primal Groudon, help take care of Pursuit-trapping Mega Scizor. Ghost-types and Solgaleo are helpful for handling Extreme Killer and Xerneas, respectively.
* Psychic Terrain setters, most notably Tapu Lele, help Psycho Boost's damage achieve nigh-unstoppable levels and give Deoxys-A an immunity to priority moves.
* Nasty Plot, combined with Psychic Terrain on the field, turns Deoxys-A from terrifying sweeper into an outright nuclear bomb with even more devastating Psycho Boosts. Given its frailty, however, it would take extreme care and proper timing to successfully pull off.
* Hidden Power Fire or Fire Punch can deal with heavily Fire-weak Steel-types, but these moves are usually outclassed by Superpower's wider coverage.
* Dark Pulse works off of Deoxys-A's stronger Special Attack, but it provides less utility than Knock Off or Pursuit.
* A suicide lead would seem viable, but it usually fails to do its job and is outclassed by Deoxys-S in that role.
Checks and Counters
**Psychic-types**: Arceus-Psychic, Mewtwo, Solgaleo, and Lunala all resist Deoxys-A's STAB attacks and have the ability to KO back. They should watch out for Dark Pulse or Knock Off, though, especially Lunala with a broken Shadow Shield.
**Priority**: Outside of Psychic Terrain, any strong priority move will easily KO it. Notable users include Arceus, Rayquaza, Giratina-O, and Mega Scizor. If they are weakened, however, Deoxys-A can KO with its own Extreme Speed. Yveltal is also notable with Sucker Punch, but as Extreme Speed nullifies Sucker Punch, this will ultimately prove advantageous to whoever can correctly predict their opponent.
**Prankster Users**: Pokemon with Prankster, like Klefki and Sableye, are great hindrances with access to moves like Thunder Wave and Will-O-Wisp to ruin Deoxys-A's sweep or longevity.
**Passive Damage**: Entry hazards, status conditions, sand, and hail are all harmful to Focus Sash Deoxys-A, slowly chipping away at it while also breaking its Focus Sash. Life Orb variants don't appreciate it either, as the residual damage can accumulate.
**Choice Scarf Users**: Choice Scarf users with a base speed of 97 or higher can outspeed and KO Deoxys-A before it has a chance to harm them.
**Dark-types**: Yveltal, Mega Sableye, and Arceus-Dark can take any hit very well, except Ice Beam for the former two and Superpower or Low Kick for the latter, and KO in return with the appropriate move. They cannot directly switch into said moves, however, or there is a chance they will KOed with an Extreme Speed or a followup Ice Beam.
**Pursuit**: Although the Pokemon that commonly use Pursuit in Ubers can all be taken out with the appropriate coverage move, Mega Scizor, Aegislash, and Alolan Muk can all pose a serious threat, being able to KO Deoxys-A as it switches out.