I've lurked for the past 5 years, but it's time to come out of my cave again. I've seen a lot of arguments anti-arena trap arguments that I believe are extremely bad and I'd like to explain why.
1. Arena trap makes even horrible pokemon good i.e. Duggy and we should expect to see trapinch and diglet do the same thing post-ban
This is a really poor understanding of what dugtrio does. Yeah, its stats are awful almost across the board, but it has a fantastic speed stat of 120 and a passable (especially this gen) attack stat of 100. The bulk really doesn't matter when you're always coming in off of a knock out, turning move, or double, and outspeed and OHKO in return with choice band because you hit 448 attack with a 100 power stab move. So yeah, duggy is really bad without arena trap but it is built to abuse this ability. Speed also means you will always go before recovery, so walls can't respond to him which really broadens what can be trapped. Duggy, especially with the lower power level and hospitable metagame almost always has like 3 things it can trap and kill every game.
The same just can't be said for trapinch or diglet. Trapinch has the same attack as duggy but has equally terrible bulk coupled by one of the worst speed stats in the game. It's bulk does matter because it never outspeeds, and its bulk is so bad it gets OHKO'd by nearly everything, necessitating eviolite which makes it hit way softer than banded duggy. The result of this bad bulk, speed and item requirement, is that trapinch is so much more specialized in what it does, and is way more comparable to magnezone (but worse, because zone is an actual pokemon without its ability). Diglet is also not even close to duggy because though it can run a band and is fast (though not nearly as fast), the banded hit is coming off of something like 55 attack so it needs to hit super-effectively to kill what it wants to kill at any reasonable percent (once again, much more specialized, not much more like magnezone or pursuit). Not being able to remove neutral targets like fairies really hurts these mons and makes them so uncomparable to dugtrio. Duggy is always banned because he punches so many holes in people's teams to enable so many sweeps, making the game feel out of your hands. In this meta in particular, he is the premier way to remove fairies and pex for hydreigon and other dangerous setup mons. Diglet and trapinch were banned in previous gens because their narrow trapping niches trapped everything stall needed in order to win i.e. heatran, band tar etc. and when these specific pokemon are down stall is nearly impossible to break. For those on the anti-arena trap side please tell me what play styles/teams are enabled by these mons, and how these teams are nearly impossible to beat with these mons removed.
2. Precedent
This gen is just so much different than previous ones that it isn't very fair to claim this. Note that this is the first time in like 5 years without chansey, mega-sableye, unaware clef, other stall staples, and very trappable glue mons or stall breakers like tran, mega-mawile, etc. The meta is wayyyy different so I don't think precedent is a particularly powerful argument as it might have been in gen 7.
3.What about DLCs
I'll break this into to parts because the first DLC point is absolutely horrendous but I think most people recognize that. "What if they give arena trap to another broken trapper?" is frankly a terrible argument. Like preemptively banning an ability because another good trapper with it might be added to the game is so silly it shouldn't be entertained. Like, we should have banned gorilla tactics in that case, because they could give us another broken mon with it.
The second argument, which is much better is "what happens when the mons mentioned above comeback?" And that is a good point, but I will just say that we should cross that bridge when we come to it because we still don't know which mons will make it back, and also moves have been removed, like hidden power, and a ton of moves have been added via TRs. I believe that preemptively banning something would be silly.
4. Trapping is inherently uncompetitive
I completely disagree and nearly everyone in the community also does too. We were okay with magnet pull and pursuit BECAUSE they are so much more limited in what they trap. We agreed that the smaller pool of mons and the content of that pool were what made those forms of trapping fair. Diglet and trapinch work extremely similarly this gen and once again are not real pokemon outside of trapping, which magnezone and tyranitar are.
5. Shadow tag was banned, not Gothitelle
Goth was really stupid and nobody will ever deny that, but not only is she good but her stage 2 is also really good, and so is wob, that literally leaves one mon, so banning tag is so much easier than banning 3 mons to leave baby goth. Baby goth also has NO niche at all. Arena trap has 3 users, one of which is comparable to goth and 2 of which just aren't, so banning just duggy is no more complex than banning arena trap and preserves 2 mons that aren't broken and have a reasonable niche.
6. Why preserve diglet and trapinch
I think this is also a really silly argument but people actually agree with this one. They aren't broken, so we shouldn't ban them. Blaziken is banned, not speed boost for this reason and others. He's banned and not speed boost because it would be banning a lot of mons that just aren't broken.
My arguments for why dugtrio specifically is broken also why diglet and trapinch are so much more limited.
1. Duggy traps a huge amount of pokemon. Diglet and trapinch trap a very narrow area of the meta and need the pokemon to be extremely hurt, or a super-effective hit. Diglet and trapinch don't trap clef, sylveon, ace, and have a way lower kill threshold than duggy does.
2. Diglet and trapinch are way more similar to magnet pull and pursuit, which were deemed competitive, than dugtrio. Again, their traping niche is really small, and unlike magnet pullers and pursuiters they aren't real pokemon outside of trapping.
3. Dugtrio has great stats that are built for abusing arena trap, diglet and trapinch just don't. Dugtrio has way higher speed and attack than either of the other options, and as a result traps so much more. Duggy doesn't have bad stats, his stats are exactly where the need to be, it's really like hating on conk for having low speed and special attack when its stats are exactly where they need to be for him to function the way he does.
4. Diglet and trapinch don't enable a superbroken playstyle to persist, like in past generations.
I'm not amazing at this game but chill around the 16 and 1700s so I really would like to hear from other people and there could be something I am missing, if diglet or trapinch do enable some broken playstyle I'd like to know, but I just don't see it right now. Thanks for listening to me (:
EDIT: fixed typos ):
Wow. An actual post with reasoning. I salute you sir. This is what I wanted to see. Thank you for taking the time to generate discussion.
Ok, let's begin.
1. While Dugtrio does have great stats to allow it to use its ability, Trapinch's bulk is not so horrendous that it can't take a hit (it has more physical bulk than Duggy before Evolite) and when you factor in the fact you have 256 EVs to invest in bulk, thanks to your speed being so worthless, Trapinch lives some surprising hits with correct investment.
0 SpA Clefable Moonblast vs. 0 HP / 248 SpD Eviolite Trapinch: 82-97 (35.4 - 41.9%) -- guaranteed 3HKO
252+ Atk Trapinch Earthquake vs. 252 HP / 4 Def Clefable: 193-228 (48.9 - 57.8%) -- 56.3% chance to 2HKO after Leftovers recovery
So with minor chip (provided by Dragapult's U-turn) and the correct investment, Trapinch beats SpeDef Clef (unless you're going to try and WishProtect stall it, which is pretty obvious and can be mostly played around by using a move other than EQ on the Protect). There are many other examples of this, but it all boils down to: "What does my team want dead?" For more on this, see below.
Diglet has going for it a 95 base speed, which is much higher than it sounds in the current meta. You mention Cinderace (or I think you did when you said ace?), well with with a Choice Scarf equipped, Diglet outruns the entire meta which lets it do things like this:
252+ Atk Diglett Earthquake vs. 0 HP / 0 Def Cinderace: 266-314 (88.3 - 104.3%) -- 25% chance to OHKO
So again, minor chip and Diglet successfully traps. This also makes Diglet an excellent revenge killer of all kinds of dangerous threats, as the target is likely chipped and easy prey, while being unable to escape. Then there's Focus Sash Reversal:
252+ Atk Diglett Reversal (200 BP) vs. 224 HP / 0 Def Tyranitar: 516-608 (129.9 - 153.1%) -- guaranteed OHKO
252+ Atk Diglett Reversal (200 BP) vs. 0 HP / 0 Def Bisharp: 560-660 (206.6 - 243.5%) -- guaranteed OHKO (so long as you beat Sucker Punch, and Diglet does get Rocks to possibly do that with)
Then, there's Choice Band.
252+ Atk Choice Band Diglett Earthquake vs. 0 HP / 0 Def Dracozolt: 342-404 (106.5 - 125.8%) -- guaranteed OHKO
Yes, this isn't a very long list agreed. But I'll get more into why this is an issue later.
2. Kinda agree, but Arena Trap is currently arguably more broken than it was in Gen 7. Rather than just dealing with threats to stall teams, Duggy's cropping up on every team style from HO to balance to deal with whatever the team needs him to. Duggy is so centralizing ATM that the whole VR A- up bar Clef and Pex is "are you not trapped by Duggy?". So Arena Trap is arguably even more distorting than before.
3. What about them indeed, TBH.
4. Now this is the clincher I think everyone's ignoring. No matter how much teambuilding and planning you throw at it, Magnet Pull will never be able to
under any circumstances trap non-Steels. So when you see a Magnet Pull mon in Team Preview, you know
exactly what it can and can't do, and are able to play around that. Whereas with Arena Trap mons, what they can and can't do is customiseable. Depending on what you need to be trapped for your given team, you can customise them for your needs. While you can have a guess at what an Arena Trap mon will do in Team Preview, you can never be fully sure what it's set up to trap (case in point: the people who actively switched their Toads into Trapinch against me after a First Impression kill expecting to ez outspeed and OHKO the Trapinch, only to lose their Toad). Also, Magnet Pull lacks the flexibility of being able to trap almost anything weakened on the fly, which is the cherry on top for Arena Trap.
While it would be easy to dismiss Pursuit by saying "but it's cut so it doesn't matter", I'll attempt to tackle this too. Pursuit is only a "soft trap" as the opponent is still free to switch if they survive the Pursuit, which means scenarios where the trapper takes multiple turns to kill/abuses the trapped mon don't take place. Also, the opponent is free to stay in, whereupon you are using a 40 BP Dark move. And if it doesn't kill unboosted and/or they are faster than you, that creates an awkward 50/50 not present with abilities. It is also predictable and not in any way customisable beyond making it do as much damage as possible.
5. From a tiering perspective, it is actually preferable to ban all the Shadow Tag mons individually (nowhere in tiering does it say we have to minimise bans), but banning the Ability is preferred because of its uncompetitive nature and how it performs basically the same on all of them. See also Moody getting banned over Glalie despite Octillery being pretty trash with it. Arena Trap is uncompetitive due it taking away a player's ability to switch, fundamentally preventing them responding to actions. It does this on all its users (note that even if you switch in and switch out your opponent cannot switch in response so you limit their actions just by existing). The lack of predictability in what you trap (See above) also leads to matchup fishing and having to second-guess when the trapper is coming in and what they are doing. For this reason, Arena Trap as an ability is fundamentally uncompetitive.
6. TBH this is a weak argument strictly speaking, but realistically it's true. We are spending time discussing two LC mons and their place in OU. It's a bit silly.
And since you asked what broken playstyle this enables, there's this mon called Dracovish which is only balanced by the fact every other team has a Water Absorber on it, and can easily make up for a mon deficit in the absence of one (though I've found in practice Pinch ends up contributing anyway in some way, even as sac fodder for a free Vish switch-in helps). And yeah, I run mine with Rain (Pinch can also trap most weather setters), so good luck without a Water Absorber.
I fully agree that my Pinch set is dumb and shouldn't exist. But Vish just happens to be the perfect storm in this case. TBH, Vish's probably banworthy anyway by itself, but being able to remove people's answer to it (and their Stealth Rocker to boot) is just stupid. Peng said it best:
That Trapinch is never going to catch on widely obviously but I firmly believe that it should not even be possible for a set like that, upon which a hard counter to one of the best Pokemon in the game, can be caught on a U-turn and beaten by such a dumb strategy. Any other cheese like that you can play around - if that Trapinch gets in vs Seismitoad and you don't have other Dracovish counterplay you literally lose the game. The ability to prevent 70% of Pokemon from switching out is uncompetitive and enables niche and near occasionally non-preventable bullshit like this
Finally, side note, even stacking Water Absorb mons doesn't prevent it as Pinch is healed by killing them thanks to Giga Drain.
Edit:Forgot something else. Arguably the reason Trapinch sees no play in lower tiers is because said lower tiers have no mons like Vish where they can carry an entire team once a singular answer is removed. That and the team has to be built towards executing the trap to a degree (See Eject Pack Rotom-H that baits in the Toad etc.), and hence requires the reward to be massive/the matchup against teams without these answers to be playable 5v6, which Vish provides, or comes closest to providing.