From the raging maelstrom rises Water Arceus. As a Water-type, Arceus must compete with the great creator of the seas, Kyogre. While the mighty Arceus may not have Kyogre's sheer power, Arceus does have many glorious qualities. Arceus's ability to move like a raging torrent is its biggest advantage, as it is able to outpace both the space-bending Palkia and the ruler of the air, Rayquaza. With Recover, Arceus can repair any wound inflicted upon its majestic form, unlike Kyogre, who is forced to use Rest to heal. Arceus is also much more devastating as a physical attacker thanks to the great Swords Dance. While Water Arceus and Kyogre may seem like rivals, one should not underestimate their offensive prowess on the same team. With Kyogre's eternal rain on the battlefield, the power of Arceus's own Water-type moves is increased to a terrifying level. Be wary against this form of the omnipotent Arceus or face its divine wrath in the form of a torrential flood that will wash all but the strongest away.
It may seem odd to use a Swords Dance Water Arceus over something like Kabutops, who has higher Speed and Attack due to Swift Swim and Arceus's EV limit, respectively. However, Arceus is bulkier than other rain sweepers, and has access to Recover, which sets it apart and makes it a force to be reckoned with.
Swords Dance allows Arceus to raise its Attack to sky-high levels and deal insane damage; after Stealth Rock, Waterfall 2HKOes even Giratina-O! Waterfall is the STAB of choice for this set as it gains "double STAB" in the rain, letting Arceus muscle through even Pokemon who resist Water with its handy 20% flinch rate. Dragon Claw is the ideal move to complement Waterfall in terms of coverage, as it hits Dragon-types that resist Waterfall for super effective damage. Dragon and Water also combine to provide phenomenal type coverage, hitting everything in Ubers for at least neutral damage. A word of caution, a 2x resisted Waterfall in the rain has more power than a neutral Dragon Claw. Therefore, Dragon Claw should only be used against opposing Dragon-types, or when facing a Pokemon with a 4x resistance to Water, such as Ludicolo or Palkia. Against Giratina-O Waterfall is the better course of action, however, as both Dragon Claw and Waterfall fail to OHKO it after a Swords Dance boost, but Waterfall has a nice chance to flinch and still 2HKOes despite the resistance. Garchomp is another Dragon that Arceus is better off using Waterfall against, as a +2 Waterfall in the rain will always OHKO, unlike Dragon Claw. Recover rounds off the set nicely by giving Arceus a way to capitalize on its great bulk. With Recover, Arceus can set up a Swords Dance or two on a wide variety of Pokemon and simply heal off any damage taken before sweeping. A Jolly nature is needed to outspeed the numerous base 90 Speed Pokemon in Ubers, as a max Speed base 90 with a Speed boosting nature outruns a neutral Arceus due to Arceus's EV limit.Team Options & Additional Comments >>>
At first glance, this set may seem inferior to Calm Mind Kyogre due to Kyogre's superior Special Attack; however, upon closer observation, one will find that Calm Mind Water Arceus has several advantages over the giant whale. First and foremost is Arceus's access to Recover, which is largely superior to Kyogre's Rest. Arceus also has more Speed than Kyogre, even with the EV limit, allowing it to always outspeed Rayquaza and set up more easily on base 90 Speed Pokemon.
The first slot of this set goes to Calm Mind, which allows Arceus to raise its Special Attack and Special Defense to obscene levels, and after a few uses, it is nearly unbreakable on the special side. The second slot depends on whether you want to use a mono-attacker set or a regular Calm Mind set. If one wishes to use mono-attacker Water Arceus, the best option is Surf due to its superior PP. If one does choose Surf, then the third slot should be Substitute, as it allows Arceus to scout for switch-ins and gives it an easier setup on foes like Blissey, who cannot break Arceus's Substitute with a single Seismic Toss. If one chooses to use Judgment for added power, Ice Beam becomes the better choice for the third slot to provide Water Arceus with better coverage. Ice Beam allows Arceus to crush the Dragon-type Pokemon it would normally struggle against, such as Palkia and Rayquaza. Arceus needs two Calm Mind boosts to even 2HKO Rayquaza with Surf because of Rayquaza's Air Lock, which negates rain and the boosts it provides. This fact is what makes considering other ways of beating Rayquaza, in this case Ice Beam, important. However, no matter what, Kyogre is always a required teammate due to its Drizzle boosting the power of Arceus's Judgment or Surf to astounding levels. Recover is recommended in the last slot as it complements Arceus's great bulk, and lets it set up on all but the fiercest special attackers by alternating between Calm Mind and Recover. Finally, Timid should always be used with this set as it allows Arceus to outspeed Pokemon like Rayquaza and Dialga, provided they aren't holding a Choice Scarf.Team Options & Additional Comments >>>
The options listed above are superior, but there are still a few other possibilities. Firstly, Shadow Claw can be used over Dragon Claw on the Swords Dance set to hit Psychic- and Ghost-type Pokemon harder, but Waterfall ensures nearly all the same KOs, and Dragon Claw is useful for coverage against Dragon-type Pokemon. Another interesting option is a bulky Water set, making use of Arceus's great natural bulk and Recover. However, it would be generally inferior to Kyogre, who may not have access to Recover, but has superior Special Attack. In general, a tank Arceus set is a bad idea due to Species Clause; one needs to use Arceus wisely. There are a near-infinite number of possibilities, but most of them are best left to other Pokemon or Arceus types. It may be tempting to use an Attack- or Special Attack-boosting nature for more power, but it is never a good idea for Water Arceus, as it needs to outspeed base 95 Speed Pokemon and below to reach its full potential.
Checks and Counters
Water Arceus may be mighty, but both sets are perfectly counterable. Without any Special Defense boosts, Arceus is OHKOed by a Choice Specs-boosted Thunder from a Pokemon with base 150 Special Attack after it takes Stealth Rock damage. Therefore, Choice Specs Kyogre, Dialga, and Mewtwo can easily switch in on Swords Dance or Calm Mind and strike Arceus down with Thunder, but they must be careful of a Ground-type switch-in. Also, Kyogre and Dialga must be aware of Waterfall's 20% chance to flinch, as they will both be 2HKOed by it after a Swords Dance boost and Stealth Rock damage. Groudon can also be a problem for Water Arceus, as it isn't always 2HKOed by Waterfall after Stealth Rock due to its ability, Drought, terminating the rain and summoning sun in its place. The Calm Mind set may be able to 2HKO Groudon, but it still hates the rain being taken away. Groudon can also cripple Arceus with Thunder Wave, or use Roar to nullify its boosts and force it to take damage from entry hazards. Grass and Electric Arceus resist Water Arceus's STAB, and can crush it with their own super effective STABs. If Arceus uses Substitute over a secondary attacking option, it will be completely walled by Pokemon with Water Absorb, like Quagsire. In addition to Pokemon with Water Absorb, Palkia will also be able to crush mono-attacking Arceus thanks to its 4x resistance to Water-type attacks and its access to Thunder. Shaymin-S can also be a problem because an Air Slash followed by Seed Flare will always kill a Water Arceus without any Special Defense boosts, and even if Arceus has a few Special Defense boosts under its belt, Seed Flare has a 64% chance to make it plummet back down.
For the Calm Mind set in particular, Latias can switch into anything Water Arceus has, Calm Mind alongside it, and strike it with Thunder for a 2HKO, while Arceus's Ice Beam fails to 3HKO a large percentage of the time, assuming they both have an equal number of Calm Minds. Calm Mind Kyogre easily counters Calm Mind Water Arceus, as it can 2HKO Arceus with Surf if they have an equal number of Calm Minds, while Arceus can only muster a 4HKO. If Arceus lacks Substitute or Refresh, Blissey can easily Toxic stall it due to its massive Special Defense and HP. Finally, Toxic Spikes are deadly to this Arceus's efficacy, particularly that of the Calm Mind set.