The Pokemon I elected to write about in this post is none other than the infamous Dugtrio! I’m going to be going out of the recommended order for this; there's a lot to talk about regarding Dugtrio and because it's such an exceptional case compared to many of the other potential candidates for this list I feel that going outside of that order would best describe how influential Dugtrio was.
As a disclaimer, this one's going to be an extremely long post as I want to make sure I'm providing a pretty convincing argument in favor of considering Dugtrio one of the top ten most influential threats of the generation; I'm also open to any feedback since there may be some details I've missed in this analysis. Without further ado, let us begin!
"We dreamed of creating the world's strongest Pokémon...
...and we succeeded."
- Junichi Masuda, moments before witnessing the opponent's Dugtrio OHKO his team's defensive backbone.
Part I: Introduction
Many unfamiliar with the history of Generation 7's OU tier may consider Dugtrio a strange thing to associate with offensive and defensive juggernauts - the majority of whom are quite literally the stuff of legends - such as Zygarde, Toxapex, Heatran, Landorus-Therian, Magearna, and Tapu Koko among many others; yet one could most certainly argue that Dugtrio, during its time in the tier, had an influence comparable to that of many of these and even more extreme than that of others.
Dugtrio's stats appear incredibly unimpressive at a glance: its defenses and HP are paper-thin, its Attack stat is extremely mediocre by any tier's standards, and while its Speed stat is very high its relatively low power in more generalist matchups and overall lack of bulk would prevent it from picking up more than a single KO. This mole's strength, however, lay in its incredible Ability: Arena Trap. In discussing Dugtrio's influence on the metagame, this Ability will most certainly come up on several occasions, and while Dugtrio is by far its best user the Ability had some implications beyond Dugtrio.
Part II: The Generation Gap
Dugtrio has played a role in the OverUsed tier ever since Abilities were first added to the series, courtesy of the incredible Arena Trap: as of the time of writing this it ranks thirteenth, at the very bottom of the A- rank, on the ADV OU Viability Rankings, sharing the rank with metagame staples like Snorlax, Jirachi, and Suicune. It functions largely as a revenge killer in that metagame; it is able to eliminate the likes of Jirachi, Magneton (which had to develop a set specifically to turn the tables on Dugtrio!), and even the oh-so dominant Tyranitar with a Choice Band boosted Earthquake or one of its coverage options. Though it was an overall weaker choice in the following generation, falling to UU, it still saw occasional usage in that generation's OU for many of the same reasons; being able to trap and eliminate Heatran as well as other Ground-weak metagame staples is a valuable niche. The fifth generation brought with it Team Preview, and this fundamentally changed how Dugtrio would function going forward: your opponent would know if you had a Dugtrio on your team immediately, but you would know if your opponent had something Dugtrio could trap and eliminate immediately. This change added a new, mental layer to battles involving Dugtrio: your opponent would have to avoid putting himself or herself into a situation in which Dugtrio could trap something important, while you would try to force a trap situation through any means possible.
Discussing older OU metagames when discussing Dugtrio's influence on Gen 7's OU metagame may seem strange, but because of how exceptional of a case Dugtrio is this is is extremely important in setting the stage for the changes this generation brought for the three-headed mole. The first of these changes was one made specifically to Dugtrio: it gained an additional 20 base Attack in the transition to Sun and Moon, pushing the stat up from a mediocre 80 (max 284 if Adamant) to a more respectable 100 (max 328 if Adamant). This change alone was extremely important, as it could now score OHKOs it previously could not: the standard Choice Band Tyranitar, for instance, is now OHKOed by Choice Band Dugtrio's Earthquake, while the new Tapu Koko would always be OHKOed by an unboosted Earthquake should it be running a strictly-offensive spread (as many did at the time) while if Dugtrio's Attack stat remained unchanged it would have a chance to survive the move. This essentially allowed Jolly Dugtrio to outdamage the old Adamant Dugtrio sets, and the Adamant Dugtrio sets to reach newer heights than any old Dugtrio set. The second change, though more general in scope, was with the addition of Z-moves: this, paired with Dugtrio's semi-unique ability to pick and choose its targets and eliminate them, made Dugtrio threatening on and to a wider variety of teams than ever before.
Part III: The Tools of the Trade
Though Dugtrio was only truly excellent because of the value of its incredibly specialized niche, it could run a plethora of different sets to even further specialize that niche. Though many sets were usually relegated to specific team archetypes, one could choose the Dugtrio set that could eliminate the most important targets: for instance, a team that centered around Mega Charizard Y could get a lot of mileage out of a Dugtrio running Screech and Groundium Z for its ability to eliminate any of Toxapex, Heatran, and Chansey, while a team that would prefer to deal with fast offensive Electric types like Tapu Koko and Mega Manectric, and even some fast and frail offensive threats that weren't weak to Earthquake like Greninja, could instead elect to run a Choice Scarf Dugtrio to outpace and KO these things. Dugtrio isn't known for having the widest movepool, but the only true constant here was Earthquake, which every Dugtrio set would run. Here's an extremely rudimentary example of what Dugtrio could be seen using during its time in OU.
As a disclaimer, I intentionally left out a fourth move for Dugtrio's Scarf set because that could be customized as one saw fit (within reason). You may as well consider the sets here "the Scarf sets, the Sash sets, and the Z-move sets." Even the Natures Dugtrio could elect to run would vary: Jolly, as mentioned earlier, could now hit harder than the previous generations' Adamant, but the newfound power from this generation's Adamant Dugtrio made for a pretty convincing argument. One could argue that it was up to preference for the most part, although Sash sets would usually prefer to run Jolly.
Dugtrio gave players that used it a lot of agency during the teambuilding process in terms of item choice, Nature choice, and moveset choice, but gave players that were weak to it a considerable headache; as mentioned earlier, each of these sets can trap and eliminate very different things.
Part IV: Dugtrio's World
In the previous generation, Dugtrio made its home primarily on Stall teams for its ability to potentially remove something that could pressure its five bulkier teammates, offensively or defensively, and was frequently paired with Mega Sableye before the latter's ban. Dugtrio was most certainly still very effective on Stall teams for all the same reasons and more, but with the changes it received this generation it could also find its home on more balanced and offensive teams. One of the most dangerous offensive cores in the later parts of the Dugtrio metagame consisted of Dugtrio, Tyranitar, and Mega Charizard Y: Dugtrio could trap and eliminate Toxapex - something that walls Mega Charizard Y completely courtesy of its typing, bulk, and access to reliable recovery - and potentially Chansey - something that walls almost any Special Attacker, Mega Charizard Y and Tyranitar could more effectively wallbreak or potentially even sweep against slower teams thereafter, and their teammates could clean up from there if these two could not finish the job. That said, as the metagame progressed players found that Dugtrio could function well alongside many cores; the ability to trap and eliminate a wide variety of targets, from Heatran to Tyranitar to Chansey to Magearna, was invaluable support for many top-tier threats.
The definition of a "counter" is something that can near-indefinitely switch in on something and wall it or force it to switch out itself: such a term is frequently associated with threats that were so versatile or so incredibly powerful that they could potentially have a move or an entire moveset to deal with another set's counters or could just 2HKO everything with the correct move. A well-played Dugtrio, however, had no counters simply because its Ability outright prevents switching out in the first place. The metagame could, however, adapt somewhat to its presence: the most well-known adaptation to Dugtrio's considerable influence was Toxapex donning a Shed Shell over the tried-and-true Black Sludge for the sole purpose of escaping from Dugtrio's clutches a single time. Tapu Lele notoriously adopted a similar tactic, also frequently running a Shed Shell instead of its many alternatives so Dugtrio wouldn't trap it. As such, Dugtrio was still very difficult to adapt to because Arena Trap's ability to trap such a wide array of targets - something notably different from Magnezone's ability to only trap Steel types - meant it was technically impossible to counter in many situations. Discerning Dugtrio's set could prove difficult and an analytical player would have to determine it through team preview, as it could prove near-impossible to directly scout for Dugtrio's moveset without allowing Dugtrio to trap and eliminate something anyway. To counter-adapt to the limited viable adaptations Dugtrio forced, players would occasionally opt to give something an Eject Button to lure in a Dugtrio-weak threat, get the equivalent of a slow U-turn off if hit, and then send in Dugtrio to dispose of it. Dugtrio's Electric immunity also provided Tapu Koko with a good reason to run U-Turn on some sets so it could get some valuable chip damage on Dugtrio while also escaping from its clutches.
Checking Dugtrio was still possible, however. The Greninjas could play a very different mindgame against Dugtrio: non-Scarf Protean Greninja naturally outpaces non-Scarf Dugtrio (the same was true if both were running a Choice Scarf, obviously) and threatens to OHKO it if it isn't Focus Sash Dugtrio, but Scarf Dugtrio could severely damage non-Scarf Protean Greninja (and Sash Dugtrio could do the same to almost any Protean Greninja). Water Shuriken Greninja (Ash-Greninja) could always pose a considerable threat to Dugtrio, however, as Water Shuriken is a multi-hit super effective priority move that will OHKO any Dugtrio variant; this is important because even a pre-transformation Battle Bond Greninja could threaten Dugtrio. This is a common theme in general: if something could attack before Dugtrio, either through Speed or through priority, it could check Dugtrio. Dugtrio would generally not be used in these individual matchups, however, so Dugtrio users would avoid forcing Dugtrio into these potentially-unfavorable situations in the first place in order to preserve it for the targets it was supposed to trap. Overall, one could argue that the best way to "beat" Dugtrio before it did its job was through careful mindgames.
To say that Dugtrio was an enormous threat is still a considerable understatement. Dugtrio proved to be so centralizing that many OU players called for it to receive a suspect test. As such, two suspect tests focused on dealing with it were issued at different times during 2017.
Part V: Suspect Testing and Dugtrio's Eventual Ban
1. The Dugtrio Suspect Test:Dugtrio was suspect tested on 9 February 2017, on the grounds that it was too centralizing a force and that, though limited to function exclusively as a frail trapper, it was far too versatile in what it could trap and eliminate to be considered healthy for the tier. This suspect test was considered rather controversial at the time: some considered a Dugtrio suspect necessary, while others thought Dugtrio was far from the biggest problem the metagame was experiencing at the time. Still others argued, contrary to the Council's original opinion, that the ability Arena Trap itself was the unhealthy element of the tier. Many players theorycrafted uses for two other Arena Trap users - the slow but strangely powerful Trapinch and Dugtrio's pre-evolution Diglett - and found that they could at least partially fill the void should Dugtrio be banned: Diglett was still relatively fast and its Earthquake could still KO the likes of Heatran and other Ground-weak threats, while Trapinch, though extraordinarily slow, boasted the same damage output as Dugtrio but also had access to Superpower to potentially break through Chansey and Ferrothorn. Though the votes were either "Ban" or "Do Not Ban," many argued that Arena Trap should've been the focus of the suspect and as such one could argue that there was a third group of voters that split themselves between the "Ban" and "Do Not Ban" sides, though this may not necessarily be completely accurate.
Ultimately, in an extremely close vote Dugtrio remained in the OU tier. The most prominent anti-ban argument appears to be that Dugtrio and Arena Trap weren't what needed to be suspected at that point in time: the terrifying Mega Metagross, with its enormous wallbreaking potential, excellent bulk, great Speed tier, and wide movepool to pick and choose its counters, was frequently cited as one of the most problematic threats in the tier. As such, something that severely threatened the archetype Dugtrio was most prominent on - and something that Dugtrio could trap and eliminate as it began to run Bullet Punch less and less frequently - getting suspected and potentially banned could perhaps fundamentally change how effective Dugtrio was in the metagame at large. Pheromosa, too, proved problematic at this point and due to its versatility as well as a blistering Speed tier that Dugtrio couldn't even contest it could pose a serious threat to many teams in general, including some Stall staples. Some argued, therefore, that Stall absolutely needed Dugtrio at that point.
Pheromosa and later Mega Metagross were suspect tested and ultimately banned, and from there the world kept a close eye on Dugtrio. It began to improve drastically thereafter. It was at this point that Dugtrio began to see use beyond Stall teams. Teams began to run Eject Button users for the sole purpose of giving Dugtrio a free opportunity to trap and eliminate something. Its Z-move sets were explored more, and people found that Dugtrio could even break through the likes of Chansey with the combination of Screech and Tectonic Rage. Many called for another suspect test, arguing that Dugtrio's ability was proving far too unhealthy for a metagame that at this point had plenty of time to adapt to its presence.
2. The Arena Trap Suspect Test:On 2 September 2017, the entire Arena Trap ability was suspect tested. The rationale for this suspect test was largely unchanged: Dugtrio was able to defeat a long list of powerful offensive threats when used on Stall teams and to break past a long list of sturdy defensive backbones when used on more offensively-inclined teams, with Mega Charizard Y being cited as one of its premiere partners on these more offensive teams. Finchinator notably mentioned that, while Dugtrio was the primary focus of the Arena Trap suspect test, Diglett saw some use on Stall teams during the Dugtrio suspect test to deal with a handful of the important threats Dugtrio was used to trap. Thus the OU playerbase was once again tasked with determining whether or not Arena Trap - and, therefore, Dugtrio - had a place in the tier. Initial reception to the Arena Trap suspect test proved much more positive than to the Dugtrio suspect months prior.
Two weeks later, Arena Trap was banned from the Sun and Moon OU tier and all lower tiers in a landslide vote, and as such Dugtrio began its long descent to the darkest recesses of the PU tier. However, controversy about Dugtrio did not conclude there: players took a retrospective look at Dugtrio's role in both the BW2 and OR/AS OU metagames and concluded that many of the elements that made Dugtrio such a centralizing threat in the seventh generation's OU tier applied to those tiers, too. Arena Trap was eventually banned from those two OU metagames as well, and as such the entire ability is currently banned from the OverUsed tier in all generations that feature Team Preview.VI: The Aftermath of Dugtrio's Reign
Dugtrio is currently in a strange spot this generation in light of the Arena Trap ban: as of now it is completely untiered, having so little usage that it has no place in even PU. It currently has a rank of B- in Smogon's new unofficial tier, ZeroUsed; at least there it has a semblance of a niche. Yet in a twist of irony, Dugtrio has a notable niche in the Ubers metagame of all places: with Arena Trap still being legal in Ubers, Dugtrio possesses the valuable niche of trapping and decimating titans like Primal Groudon and Dusk-Mane Necrozma with its tried-and-true Groundium Z set. Dugtrio, while technically legal in OverUsed as only Arena Trap is banned, serves no purpose except as a reminder of its massive influence from days long past. But few if any familiar with the SM/USUM OU metagame, from casual fans that were introduced to the metagame through influencers like Blunder, Pokeaim, and False Swipe Gaming to Smogon's most elite tournament players, can deny just how impactful Dugtrio was during its stay in the tier.
Few if any Pokémon prove so impactful in a metagame that they can influence its role in past metagames; yet here Dugtrio stands, for its influence here was so great that its flagship ability was retroactively banned from two more OverUsed metagames that had since run their course.
EDIT 7/14/2019: I realized now that I forgot to include Shed Shell Tapu Lele as a common "countermeasure" to Dugtrio even though I discussed it with some of the folks in the OU Discord and we all brought up the absolute degeneracy of Shed Shell Lele to deal with Arena Trap.
