The Creator oozes with the scum and filth He has deemed you to be in His toxic form. The might of the pestilential deity vanquishes His victims faster than the deadliest of poisons. While the virulent master cannot scratch the hide of His Steel-type nemeses with His filthy sludge, or stomach the telepathic onslaughts of His arch-nemesis Mewtwo, His viscous hide protects Him from the potent barrage of draconic assaults His underlings unleash. The venomous creator even consumes all forms of Toxic and Toxic Spikes within His mighty gullet upon entering the battlefield. Bow before your corrosive maker or risk incurring His putrid Judgment!
Poison Arceus's main advantage over its other formes is the ability to remove the dreaded Toxic Spikes; for that reason alone, it makes a fantastic supporter. With access to a reliable healing move in Recover, as well as great support moves, Poison Arceus can stall out multiple threats. Furthermore, thanks to its Poison typing, Poison Arceus can swallow any Fighting-type move from the likes of Terrakion, Heracross, and Lucario. Will-O-Wisp is a great move that helps Arceus weaken its opponents while severely crippling physical attackers, while Reflect never misses and halves damage to the team from physical attacks for five turns. Roar fits well in the final slot to prevent your opponent from setting up, and racks up residual damage; alternatively, Stealth Rock can be used if nothing else on your team can set it up. As Poison Arceus usually doesn't need coverage moves on this set, Perish Song can be used instead to ensure victory over endgame sweepers, provided it can stall out at least three turns.
Will-O-Wisp is the preferred status move because this set is geared to counter physical sweepers such as Swords Dance Ghost Arceus and Rayquaza. Though Toxic and Thunder Wave both have their merits, Will-O-Wisp has the advantage of crippling the feared Choice Band Groudon, who would otherwise stomp Arceus to pieces. Ice Beam's utility and coverage in Ubers make it the primary choice for an attack. It also deters Groudon from switching in, while OHKOing both Rayquaza and Garchomp. Flamethrower prevents Steel-types such as Ferrothorn, Forretress, and Skarmory from setting up on Poison Arceus for free.Team Options & Additional Comments >>>
Poison-type moves are resisted by four types, not including Steel, while only hitting rarely-seen Grass-types super effectively. However, Poison Arceus's immunity to Poison-type moves, especially Toxic, allows it to set up on both Chansey and Blissey with impunity. Apart from absorbing Toxic Spikes, this set plays identically to almost every other Arceus forme's Calm Mind set.
The choice between Sludge Bomb or Judgment is up to the user. Sludge Bomb is the preferred attack, because it exchanges only 10 Base Power for a 30% chance of poison, which could secure victory in a Calm Mind war. However, this poison chance might backfire. For example, if a physical attacker such as Extreme Killer Arceus switches in and gets poisoned, Poison Arceus will no longer be able to cripple it with a burn; this makes Judgment a very solid option. Judgment also has more Base Power, but that's subsidiary, as this set does not focus on immediate power. Focus Blast is recommended in the second slot due to its ability to hit most Steel-types for super effective damage. Fire Blast is another option to roast Ferrothorn, Forretress, and Skarmory in one blast, but in exchange, Arceus loses the ability to smack Dialga hard, and Heatran is now immune to both of its moves. Ice Beam, on the other hand, trades coverage on Steel-types for a hard hit on the plethora of Dragon-types in Ubers, most notably Giratina, who resists Sludge Bomb.Team Options & Additional Comments >>>
Two changes can be considered on the support set: first, Judgment or Sludge Bomb can replace Ice Beam or Flamethrower for a stronger attack, but having a Poison-type move as Arceus's only attack is horrible in Ubers. Second, Thunder Wave or Toxic can be used over Will-O-Wisp, but Will-O-Wisp's ability to cripple Poison Arceus's biggest threats in Groudon and Garchomp makes it the superior choice. Finally, Earthquake can be used to eliminate Heatran in one hit.
Checks and Counters
Mewtwo is definitely a huge threat to Poison Arceus, as it is able to switch into any of Arceus's unboosted moves, and Psystrike OHKOes the Calm Mind set and 2HKOes the support one. Mewtwo can even set up its own Calm Minds while taking little damage, threatening not only to destroy Poison Arceus, but also to take out your entire team. Additionally, Will-O-Wisp will not even cripple Mewtwo as it is specially offensive. Heatran and other Steel-types are a pain for Arceus because it will have to rely on Focus Blast's shaky accuracy in order to take care of them. Steel Arceus is especially notable as not only can it set up Calm Mind boosts alongside Poison Arceus, it can also use Roar to phaze Poison Arceus out. However, Steel Arceus risks being OHKOed by Fire Blast in the sun, or a +1 Focus Blast. Ground Arceus and Psychic Arceus are also great counters, as they can strike Poison Arceus hard with their super effective STAB moves and KO without boosts; Ground Arceus also resists Poison Arceus's STAB.
Groudon can shatter Poison Arceus's thick hide with a mighty Earthquake; both Rock Polish and Choice Band Groudon will always OHKO non-support Poison Arceus with Earthquake, but must avoid Will-O-Wisp. In a similar manner, Garchomp can pose a threat if Arceus lacks Ice Beam or Will-O-Wisp, as Choice Scarf Garchomp will 2HKO with Earthquake. Excadrill is immune to Poison Arceus's STAB, but must be wary of Fire Blast or Focus Blast. In sandstorm, however, it outspeeds Poison Arceus and can OHKO Calm Mind variants with a super effective Earthquake. Reshiram and Kyogre can OHKO the support set with their mighty STAB attacks, as well as the Calm Mind set without too many boosts. Calm Mind Kyogre can set up alongside Arceus and win the war with its superior special stats and weather-boosted attacks. Ho-Oh can smash Poison Arceus with its mighty Sacred Fire or repeated Brave Birds while laughing off most attacks, but Ho-Oh will not enjoy facing support variants packing Roar and Stealth Rock, because Ho-Oh absolutely hates taking Stealth Rock damage.