[OVERVIEW]
Possessing High high Attack and Speed stats along with access to a powerful base 140 base power Psychic-type (that's its only type) STAB move in Psycho Boost, Deoxys-Attack fits very well on Hyper Offensive-focused hyper offense teams as a check to fast Pokemon such as Choice Scarf Landorus-Therian or and Mega Diancie. Its high-damage Psycho Boost hits most threats neutrally, which, when combined with Fighting-type coverage, covers a major significant portion of the metagame. On the other hand, Deoxys-Attack has a poor matchup against Mega Kangaskhan, which threatens Deoxys-Attack with Fake Out and can also can OHKO Deoxys-Attack it through sash its Focus Sash with a Parental Bond-boosted Sucker Punch. In addition, Psycho Boost and Superpower drops lower its Deoxys-A's damage output, making Deoxys-Attack it a poor answer to bulkier threats in the metagame. Its extremely poor defenses leave it susceptible to even the weakest of moves and force it to run Focus Sash to compensate for them. Deoxys-Attack is especially vulnerable to priority attacks, as they will break bring it down to its sash Focus Sash or finish it off after its sash Focus Sash has been broken before Deoxys-Attack it can move. (Extreme Speed tho?) Opposing speed control such as Trick Room, Tailwind, and Thunder Wave take away Deoxys-Attack's speed Speed advantage and ability to function as a threat, which is its biggest asset.
[SET]
name: Fast Mixed Attacker
move 1: Psycho Boost
move 2: Superpower
move 3: Extreme Speed / Knock Off
move 4: Detect
item: Focus Sash
ability: Pressure
nature: Naive
evs: 4 Atk / 252 SpA / 252 Spe
[SET COMMENTS]
Moves
========
Psycho Boost is Deoxys-Attack's main STAB attack, OHKOing: it usually OHKOs most things Pokemon that it hits neutrally, except for particularly bulky Pokemon in the meta such as Suicune or and Zapdos. Superpower lets Deoxys-Attack cover Steel- and Dark-Types Dark-types such as Heatran, Bisharp, and Hydreigon that resist or are immune or aren't hit very effectively by to Psycho Boost. Extremespeed Speed is a +2 priority move, (AC) which allows Deoxys-Attack to outspeed move before opposing priority attacks moves, such as Sucker Punch, (AC) while also being higher priority than Talonflame's Brave Bird, and or Thundurus's Thunder-(RH) Wave, letting Deoxys-Attack revenge kill or deal a last chunk of damage to these threats priority users or at least deal damage to them before it faints. Knock Off is an option that enables Deoxys-Attack to hit Psychic-Types Psychic-types such as Latios and Cresselia as well as Aegislash, which resists Psycho Boost and is immune to Superpower. Detect is an all-around good move on in Doubles Pokemon OU, allowing Deoxys-Attack to avoid being targeted while its partner maneuvers to improve the position for Deoxys-Attack does whatever it wishes. (What even... I'm not even too happy of the edit I proposed. Think about what you're trying to say here.) In addition, Detect can be used to stall out field conditions such as weather, Trick Room, or and Tailwind.
Set Details
========
Maximizing Special Attack enables Deoxys-Attack's Psycho Boost to do deal the most damage possible. A Naive nature combined with and (Now if P^2 checks this she won't try to murder you) maximum Speed EVs lets it Deoxys-A outspeed Adamant Choice Scarf Landorus-Therian and some +1 Pokemon, such as Blaziken and Volcarona. The remaining 4 EVs are put into Attack for a slight boost for to Deoxys-Attack's physical moves. Alternative An alternative EV spreads such as of 48 in Atk / 208 SpA / 252 Spe guarantees an Superpower OHKO on Hydreigon with Superpower, and another EV spread with of 112 in Attack / 144 SpA / 252 Spe can be used to OHKO guarantees a Knock Off KO on Latios with Knock Off.
Usage Tips
========
Deoxys-Attack's extremely poor bulk means that it can't switch in on any opposing moves, so bring it into play primarily as a lead or when after a teammate faints. Deoxys-Attack works best against other Hyper-Offense Pokemon hyper offense teams, as it is essentially the fastest viable Pokemon in the metagame, letting it outspeeding and KOing many Pokemon before they can act, so utilize it to keep opposing offensive threats such as Keldeo and Landorus-Therian out of the fight. Avoid using Deoxys-Attack to confront bulky threats it has difficulty fighting breaking down such as Suicune or and Aegislash. In addition, Deoxys-Attack needs to avoid opposing speed control effects such as Trick Room, Tailwind, and Thunder Wave, as these cripple Deoxys-Attack's its offensive pressure by forcing it to move later slower. Keep it paired with offensively-(AH)focused Pokemon, (RC) so that it can maintain the offensive pressure necessary to keep the opponent on the back foot opposing team at bay in terms of momentum. When using Deoxys-Attack, one should be conscious of how the stat drops from Psycho Boost, Superpower, and Intimidate severely cripple Deoxys-Attack's its damage output; switching it out allows it to refresh restore its damage output when necessary or convenient. Be aware that that possible chip damage from switch-ins with Rocky Helmet or Iron Barbs on Deoxys-Attack's Superpower or Extreme Speed can break its Deoxys-A's Focus Sash or KO it after it has used its Focus Sash should it hit the switch-in with Superpower or Extreme Speed.
Team Options
========
Deoxys-Attack appreciates being paired with offensive Pokemon, (RC) such as Keldeo or and Talonflame, which help it can keep up offensive pressure and appreciate Deoxys-Attack its ability to threatening opposing Pokemon such as Landorus-Therian or foes like Mega Diancie. (You talk about Lando-T in the very next sentence, so...) In addition, Pokemon that appreciate Choice Scarf Landorus-Therian removed, such as Mega Charizard-(RH)Y or and Mega Diancie, are given room to breathe with greatly benefit from having Deoxys-Attack as a partner. Fake Out support users such as Mega Kangaskhan compliments Deoxys-Attack greatly, as it appreciates the free turns that Fake Out provides. Pokemon like Keldeo have with good matchups against Aegislash and Mega Kangaskhan, two of Deoxys-Attack's worst matchups biggest threats, such as Keldeo which can 2HKO Aegislash and OHKO Kangaskhan, work very well with Deoxys-Attack. In addition, Keldeo can not only 2HKO Aegislash with Hydro Pump and OHKO Mega Kangaskhan with Secret Sword, but it can also use Quick Guard or (use "and" if Keldeo runs these moves on the same set) Taunt, which alleviates Deoxys-Attack's weaknesses to priority moves and Trick Room, (AC) respectively. Ghost-types such as coverage in the form of Aegislash or and (Mega?) Gengar helps Deoxys-Attack against Psychic-types such as Jirachi and Cresselia as well as against opposing Aegislash. Redirectors (are you sure this is a coined term?) such as Amoonguss or and Jirachi alleviate Deoxys-Attacks frailness Deoxys-A's frailty while also having good matchups against bulkier threats that it struggles against. In addition, bulky redirectors they appreciate Deoxys-A clearing offensive threats being cleared out of the way by Deoxys-Attack.
[STRATEGY COMMENTS]
Other Options
=============
Ice Beam is an option that OHKOes Landorus-Therian without having the SpA drops of dropping Deoxys-A's Special Attack like Psycho Boost. However, in general, the other coverage options typically work better for either giving Deoxys-Attack the ability to out-priority other threats such as Sucker Punch and Talonflame Brave bird in the case of Extremespeed or helping Deoxys-Attack cover Aegislash and Psychic-Types such as Cresselia and Jirachi in the case of Knock Off Deoxys-A's usual moves are generally more useful. (Yipes.) Life Orb greatly augments Deoxys-Attack's damage output, but forgoing sacrifices Focus Sash's sacrifices its ability to let Deoxys-Attack take a hit.
Checks and Counters
===================
**Typing Advantage**: Aegislash and Jirachi can both take Deoxys-Attack's Psychic- and Fighting-type coverage very well, while taking advantage of Deoxys-Attack's frailness moves easily and capitalize on its frailty.
**Faster Pokemon Speed (this is the special DOU tag)**: Priority attacks, (RC) such as Fake Out, Talonflame's Brave Bird, or and Mega Kangaskhan's Sucker Punch are faster than go before Deoxys-Attack's attacks excluding bar Extremespeed Speed, and thus they can impact the field by KO'ing possibly KOing Deoxys-Attack or its partner before Deoxys-Attack either of them can move. Certain very high speed fast threats, most notably Jolly Choice Scarf Jolly Landorus-Therian, while uncommon, nullify Deoxys-Attack's most important advantage: (remove colon) in its speed Speed; however, such fast threats are uncommon.
**Speed Control**: Tailwind, Trick Room, Thunder Wave, and Icy Wind each all reduce Deoxys-Attack's offensive pressure presence by forcing it to move later slower, with Icy Wind also breaking Deoxys-Attack's Focus Sash in the process.
**Intimidates and Burns**: While Deoxys-Attack's main STAB is Psycho Boost, (RC) is a special move, Deoxys-A still relies heavily on its physical attacks. As such, Intimidate and Will-O-Wisp users, (RC) such as Landorus-Therian, and Will-O-Wisp from Pokemon such as Rotom-Wash Rotom-W, respectively, can heavily reduce the power of Deoxys-Attack's physical moves cripple it.