Azumarill

Huge Power
Doubles Attack.
Thick Fat
Halves Ice and Fire damage.
Type Tier
Water UU
Statistics
Min- Min Max Max+
HP
100
- 341 404 -
Atk
50
122 136 199 218
Def
80
176 196 259 284
SpA
50
122 136 199 218
SpD
80
176 196 259 284
Spe
50
122 136 199 218
Name Item Ability Nature

SubPuncher

Leftovers Huge Power Adamant
Moveset EVs
~ Substitute
~ Focus Punch
~ Hidden Power Ghost
~ Sing / Encore
252 HP / 252 Atk / 4 Spe

This set is simple to use and it can actually hurt. Waters and Blissey will not be able to break this Substitute easily, and in the meantime Azumarill dishes out really high Attack Focus Punches. Hidden Power Ghost is for Gengar and other Ghosts, it should 3HKO most Dusclops. Sing and Encore can both buy you some extra time to Substitute or Focus Punch.

This is the set you should be using for standard play. In UU, this set is harder to use because most Pokémon are either really offensive or use Toxic, and nearly everything is faster than Azumarill. Gligar and Solrock sort of wall this set, but Azumarill learns Ice Beam and STAB Water moves to remedy that.

Name Item Ability Nature

Choice Bander

Choice Band Huge Power Adamant
Moveset EVs
~ Focus Punch
~ Frustration
~ Hidden Power Ghost
~ Iron Tail / Hydro Pump
240 HP / 244 Atk / 24 Spe

If you can predict, this might work. Azumarill is really slow and has low defenses though, and no STAB on any physical move. Like with the first set, it should be brought in on Waters. Focus Punch can do major damage sometimes.

Other Options

Hydro Pump or Surf can be used to try and beat physical walls like Skarmory in standard and Solrock/Gligar in UU play. Attract, like Sing and Encore, can buy you more time to Focus Punch. Light Screen supports the team against the Electrics Azumarill hates, while Charm and Tickle help against physicals. Icy Wind slows down opponents, it takes a while for Azumarill to catch up with it but your team might appreciate it. Perish Song forces switches, Present is a fun gamble that will either hurt the crap out of your opponent, do shitty damage or heal them. Azumarill is too slow to Belly Drum effectively but it's there.

EVs

Add 24 Speed EVs and it outspeeds Swampert. Max out HP for 101 HP Substitutes, which are unbreakable by Night Shade and Seismic Toss. 401 HP is fine if you don't have Substitute. Besides all this, boost Attack as much as you can.

Opinion

Azumarill has an easy time coming in on attacks in standard and might actually hurt the opponent, however it is really flawed in that it lacks physical STAB, or good stats not named HP or that auto-boosted Attack to begin with. It's good on paper, but isn't used much for a reason.

Counters

In Standards, it pretty much gets walled by Weezing and possibly by Claydol (though Hidden Power Ghost and Water hurt). Skarmory could possibly wall it, as long as it doesn't eat too many Focus Punches or Hydro Pumps. Dugtrio would also spell trouble on the incoming to avenge one of it's fallen teammate if you don't have a Substitute up. Gyarados and Salamence also do a fair bit of walling as they resist his most powerful attack and can Intimidate it. Gengar is annoying if you don't Hidden Power Ghost or Substitute on the switch as he's immune to Normal and Fighting and often packs Thunderbolt.

In UU, Gligar and Solrock, by themselves or used together, wall this Pokémon quite effectively. A fast Electric starter could also just end it from the start and Vileplume can take any of its non STAB attacks. Sableye sadly walls this Pokémon from head to toe and can heal off any hopes of CHing with Hidden Power Ghost and whatnot.