With physical STAB, the equivalent of 150 base Attack, decent defenses, and convenient typing, Azumarill can run circles around unprepared teams. With a Choice Band, it can break down even UU's bulkiest walls with the appropriate move, 2HKOing Slowbro, Milotic, Regirock, Registeel, Steelix, and Spiritomb. Substitute variants can take advantage of a wide range of defensive Pokemon including Chansey and Registeel, breaking the mid-game wide open with a massive Attack stat and decent coverage. Azumarill has a niche on offensive teams due to its good defenses, ability to take hits, and STAB priority move. Although Aqua Jet somewhat alleviates Azumarill's Speed concerns, its subpar Speed is still its greatest shortcoming.
Azumarill's convenient resistances to Water-, Ice-, and Fire-type attacks paired with respectable 100 / 80 / 80 defenses grant it multiple opportunities to switch in and inflict damage. Waterfall and Return provide great type coverage; the attacking combination of Water + Normal is resisted only by Shedinja (in UU) and Empoleon (in OU). Double-Edge's additional power can be useful at times (it allows Azumarill to sometimes 2HKO Slowbro with Stealth Rock support), but in general, the recoil sacrifices too much of Azumarill's bulk. Aqua Jet allows Azumarill to function as a potent revenge killer and even gives it a chance at a late-game sweep once Water-type resists are weakened or eliminated. The last slot is allocated for type coverage; Ice Punch helps Azumarill combat Venusaur, Tangrowth, and Altaria switch-ins, while Superpower gives a super effective hit on the likes of Registeel.Team Options & Additional Comments >>>
While the Choice Band set is dependent on prediction to inflict massive amounts of damage, this set takes advantage of Azumarill's ability to create 101 HP Substitutes to function more as a team player in wearing down the opponent.
The first two moves are self-explanatory, and Waterfall provides a reliable STAB attack. However, Ice Punch can be used to hit Venusaur and other Grass-types hard. Aqua Jet is the preferred option in the last slot, as it allows Azumarill to reliably revenge kill low-HP opponents and threaten Fire-types such as Houndoom, Ninetales, Arcanine, and Magmortar. Azumarill can also use Aqua Jet and its low Speed to garner a free Substitute: use Substitute as an attack from a faster but weakened opponent hits Azumarill, then Aqua Jet for the KO before the Substitute is broken. Encore is also an option to help Azumarill set up a Substitute more reliably and rack up Spikes and Stealth Rock damage; it also stops RestTalkers such as Milotic in their tracks. Finally, Toxic can be used to cripple Slowbro and Slowking, which easily switch into this set and wall it.Team Options & Additional Comments >>>
RestTalk Azumarill is a great example of a tank, as it's able to inflict significant damage to opponents while retaining great bulk. Rest and Sleep Talk are the two most important moves of the set as they offer Azumarill several advantages: a somewhat reliable recovery move, safety against some crippling status, such as burn and poison that could turn Azumarill into setup fodder, and the ability to keep attacking the opponent while asleep. Waterfall is a powerful and reliable STAB attack that can dent everything that doesn't resist it. The final slot brings the only choice one should consider when using this set. Return is the preferred move, because even though it offers less power than Double-Edge, it doesn't have recoil, thus providing Azumarill with more durability. Since Water- and Normal-type attacks offer very good neutral coverage, Azumarill won't find itself being walled by many Pokemon in UU.Team Options & Additional Comments >>>
If you don't care about using moves with 90% accuracy, Aqua Tail is a stronger alternative to Waterfall and can be substituted on any of the sets. Leftovers is a viable option instead of a Choice Band on offensive teams looking to capitalize on Azumarill's bulk and resists; this makes it harder for Pokemon like Toxicroak or Mismagius to set up on Azumarill, but obviously comes at the cost of some power—this makes Toxic an attractive option in conjunction with Leftovers. Sing can be used by Azumarill to send its counter to sleep, but it is generally too unreliable.
The primary EV spread given in the sets is optimal. Azumarill won't be winning Speed awards any time soon, so maximizing HP and Attack makes the most of its bulk and powers up its attacks. However, moving a few EVs into Speed is an option to outspeed other neutral-nature base 50s who may invest slightly in Speed, including Regirock, Registeel, Chansey, Hariyama, and Tangrowth. Be sure not to take any EVs out of HP for the SubPunch set, though, as 252 EVs are required to allow Azumarill to create 101 HP Substitutes. Using 84 Speed EVs outspeeds minimum Speed base 60 Pokemon such as Clefable and Weezing. On the RestTalk set, the last four EVs are placed into Special Defense to ensure Porygon2 doesn't get a Special Attack boost from Download.
Checks and Counters
Slowbro stands out as Azumarill's number one counter. It resists all of Azumarill's commonly used moves except for Double-Edge / Return and has access to reliable recovery. Despite this, Slowbro must beware of Toxic, since a Slowbro inflicted with Toxic is essentially neutered (and can be stalled out by Substitute if Slowbro lacks Psychic or Hidden Power Electric). In the same vein, defensive variants of Milotic fare relatively well but risk a 2HKO from a Choice Band-boosted Double-Edge. However, Milotic actually outspeeds Azumarill, meaning it can escape the 2HKO by abusing Double-Edge's recoil damage with Recover, activating Marvel Scale through Rest, or KOing Azumarill with Hidden Power Electric or Grass.
Venusaur sports a resistance to Waterfall and Focus Punch and can strike back with powerful STAB Grass attacks or Leech Seed and recover lost HP with Synthesis. With an immunity to Azumarill's STAB, Water Absorb Pokemon are also fine counters. Poliwrath can use Azumarill as an excuse to start using Bulk Up while Encoring Azumarill's Substitute, while Quagsire can Curse. Lapras has a massive HP stat, higher Speed, and access to Thunderbolt, but it will have to beware of Stealth Rock and the possibility of taking a heavy hit from Superpower or Focus Punch. While Toxicroak is also immune to Water attacks because of its ability, Dry Skin, its relative physical frailty means switching it directly into Azumarill is not recommended. However, it does sport a resistance to Fighting-type attacks, which allows it to more easily set up on a Choice-locked Superpower or a Substitute Azumarill without Encore.
Weezing is never 2HKOed by Waterfall and can force Azumarill out with the threat of Will-O-Wisp or Thunderbolt, but it lacks reliable recovery. Tangrowth, possessing defensive stats that make Skarmory a tad green, can defeat Azumarill even if it has a Choice Band and Ice Punch (but will lose if it has taken previous or residual damage). Altaria works against variants without Ice Punch, resisting the entirety of Azumarill's moveset except for Double-Edge. Luxray can switch in easily thanks to Intimidate and threaten with a STAB Thunderbolt.