As the only fully-evolved user of Arena Trap, Dugtrio possesses an important niche in the OU metagame as an effective trapper and revenge killer. It performs both roles really well due to its blazing Speed and good offensive movepool. However, Dugtrio's mediocre base Attack holds it back because it lacks the power to break through bulkier Pokemon, which are commonly found in the OU environment. Dugtrio's terrible defenses also mean that it won't be able to take even the weakest priority move, and Choice Scarf users can easily put an end to it despite its very high Speed. The transition to BW2 has turned OU into a much more offensive metagame, however, and there are many threats out there begging to be trapped by Dugtrio. Don't let this Pokemon's bad overall stats hold you back, because it can be incredibly effective when used correctly.
Reversal Dugtrio is an effective trapper and revenge killer. With threats such as Terrakion, Volcarona, and Jirachi around every corner, Dugtrio's ability and movepool can be quite handy, generally putting an end to the aforementioned Pokemon. However, Dugtrio's greatest selling point is its ability to easily defeat common weather inducers; Ninetales and most Tyranitar fall victim to Dugtrio, and it can also deal significant damage to Politoed. Removing the opponent's weather can easily swing the match in your team's favor.
A full-powered Reversal is Dugtrio's strongest move even after factoring in Earthquake's STAB boost, and its main use is to shut down Tyranitar and Terrakion as well as deal a nice amount of damage to offensive Politoed. Earthquake is Dugtrio's most powerful STAB move and its strongest choice when at full HP. Its main use is to defeat Ninetales and Heatran, but it is also a great move to use against other common threats such as Jirachi and Tentacruel. Stone Edge is a great coverage move that defeats Volcarona and deals nice damage to Flying-types, which avoid Arena Trap. The last slot depends on what your team needs the most. Stealth Rock can be set up easily while Dugtrio's Focus Sash is intact, giving your team a nice advantage. However, Memento is also a great option to cripple whatever switches into Dugtrio after it kills what it's supposed to, and it provides a nice setup opportunity for one of its teammates. Sucker Punch can be used as well, and it is a decent priority move that helps against Pokemon such as Latios.Team Options & Additional Comments >>>
A Choice Band set is Dugtrio's most viable other option, turning it into a strong and threatening revenge killer right off the bat. This is actually the only set that always defeats Blissey one-on-one, which is pretty important. Unlike other Choice-locked Pokemon, Dugtrio avoids the need to use prediction via Arena Trap. Dugtrio can also make use of some other items, such as Life Orb and Expert Belt. Life Orb allows Dugtrio to hit harder and doesn't turn it into setup bait like Choice Band, while Expert Belt can be used to fake a Choice Item; it scores an OHKO on Chople Berry Tyranitar with Reversal most of the time and also allows you to usually OHKO Terrakion with Earthquake. A Choice Scarf set can also be used to overcome enemy Choice Scarf users, such as Terrakion and Heatran, and some +1 Speed Pokemon, such as Volcarona, with hazards on your side of the field; it can also pull off quick Mementos late-game to help a teammate sweep. However, without Life Orb or Choice Band, Dugtrio will lack the strength to KO many important threats.
Aerial Ace can be used to remove Virizion, Breloom, and Heracross. You can also use Toxic to cripple common Dugtrio switch-ins, such as Hippowdon, Politoed, and Latias. Hidden Power Ice is a bit gimmicky, but it allows Dugtrio to break Gliscor's Substitutes, which can sometimes be useful. Because Dugtrio is a Pokemon that itches for additional strength, running an Adamant nature is viable, although you'll miss the Speed boost from a Jolly nature greatly when trying to defeat Starmie, Keldeo, and Terrakion.
Checks And Counters
By definition, Dugtrio has no counters if it is revenge killing grounded enemies, because counters need to switch in. Although it easily defeats common threats, Dugtrio struggles against most OU Pokemon due to its low defenses and lackluster base Attack.
Skamory, Forretress, and Cloyster can lay down Spikes while Dugtrio can't do much in return, and Cloyster can also set up Shell Smash. Mamoswine and Weavile can easily KO Dugtrio with priority Ice Shard, and the latter also packs a strong Pursuit if Dugtrio tries to switch out (though both have to watch out for Reversal). Azumarill easily defeats Dugtrio with priority Aqua Jet. Flying-types and Pokemon with Levitate can avoid Arena Trap and Earthquake, which means Dugtrio will have troubles with them. Two prime examples of this are Dragonite and Bronzong, as both are able to set up on it. Moves that hit multiple times, such as Breloom's Bullet Seed and Cloyster's Icicle Spear, can break through Dugtrio's Focus Sash and easily KO it. Most bulky Water-types, such as Vaporeon, Rotom-W, and Politoed, can take Dugtrio's moves and KO it back. Porygon2, although rare, deserves a mention, as it can use Trace to copy Arena Trap and dispatch Dugtrio with a strong Ice Beam. Without Aerial Ace, Breloom and Virizion take little damage from Dugtrio's moves and can easily KO it back. Walls like Hippowdon and Gliscor can use Dugtrio as setup bait, as can Rock Polish Landorus and Double Dance Landorus-T. It is also worth noting that although Dugtrio is a great weather inducer trapper, it has problems against Hippowdon, Abomasnow, and defensive Politoed.
Air Balloon and Shed Shell severely hinder Dugtrio's trapping and revenge killing ability. Anything faster than Dugtrio can easily KO it most of the time, which means that Choice Scarf users and priority moves are really troublesome for it. A common mistake for Dugtrio is switching into a Pokemon that is unexpectedly holding a Choice Scarf.