I don't really have the time to bother getting reqs for this one, though gonna throw in my two cents to see if more people can lean towards banning Dugtrio from RU, since it's a pretty cancerous thing that starts from the teambuilder and makes itself a very dangerous opponent that you can't slip up against or it can easily decide a match upon slipping up or something.
First off let me state I'm not naturally against trapping in general except for when it's plenty obvious that the trapper has a superior advantage against much of a metagame's usable Pokemon, which at the moment Dugtrio has some pretty favorable match-ups against many common offensive Pokemon and a variety of the defensive and bulky ones that anchor teams.
I mean it looks weak and all, but switching is a main mechanic of the game and it can easily abuse how big switching is in this tier, especially when it's combined with hazards. The RU tier doesn't all that great hazard removers, it's basically Flygon and Blastoise, occasionally Hitmonlee (but when do you actually ever bother spinning when you spam HJK and or Knock Off and profit?) then some niche options in keeping them off like Xatu, Golbat, Togetic, Hitmontop, maybe find a way to use Mantine, Pelipper, or Skuntank, but yeah outside the top 2 every other one is kind of meh overall in the tier right now. All it takes is having SR up and having a team that can threaten Pokemon off the field to go to better options, and that damage stacks up. It stacks up eventually to a point that you can't let Pokemon who could normally tank an EQ from Duggy fall below a certain threshold or it's very open to being revenge killed, or in the case of combining with Volt-Turn tactics, just use it to trap and kill when the damage from your attack puts it in kill range for EQ and continue as normal for the match if that's all you need to do. Seeing as Steel and Rocks are generally U-Turn absorbers, Dugtrio makes for an excellent partner with a few of the U-Turners in the tier to get rid of certain threats like Diancie and Registeel safely. Stuff like Virizion and Venusaur who act as Volt Switch absorbers for some teams have to be careful seeing as AA Duggy can one shot Viri, and pairing a Volt Switch user with Duggy and something that you can switch to always force Venusaur back out immediately again can against stack some damage in favor that it can be difficult that when the time comes to kill Venu, Duggy shouldn't have a problem after a few times.
Pretty much everything on Duggy has already been said. Heck
EonX has said pretty much everything I'd have said on it here and in the Alo thread regarding Dugtrio's role for teams. EQ is a very good neutral move against many of the tier's common offensive Pokemon, AA is your guaranteed Virizion removal, the other two moves are just a mix of what could be useful like Memento when/if Duggy removes a threat to what can be a team sweep for certain set up sweepers, Sucker for priority before death, Sub to outpredict the only answer priorities for some teams that use Sucker Punch meaning you can get another free hit or two, Pursuit to get something like Hoopa (who imo is also fricking ridiculous). Though one option that wasn't on that can also be helpful to a certain extent is Protect as a 4th option. Good to scout against potential Scarf users, that way you can make an even better switch prediction or in the case of an opponent's answer being Scarf Drapion who might have a shot to Pursuit you if the potential to kill is greater than the spam of Knock Off (which would kill Duggy anyway) gives you an out against them and since Pursuit doesn't kill Duggy if you aren't switching him and you can revenge fire a EQ. Also useful against some stuff like Scarf Medi who might just out and out HJK if the team doesn't have a ghost to deter it from spamming the move, great way to mess with those kind's of users tbh if you feel frisky to try it.
I will relent that for some that don't think Duggy might not be broken that there are things that make it's effectiveness kind of average if you combine them all together on a team, without realizing it having some levitate users together, or some of the bulkier Pokemon that find neutrality to EQ and can generally shrug it off due their bulk, but the thing with Duggy is well it's picking what it wants to trap and when it can trap it. If there's something that is generally a problem for a team to win efficiently, Duggy can more than likely trap it and get rid of it for a team. It honestly doesn't care about what something can tank it, seeing as you won't generally get it in until after Duggy's done it's job if it has its way through various tactics to get it in. Once it's done it's job then Duggy isn't relatively needed anymore for support and can just be foddered off by weakening something before dying or giving something a free turn with the use of Memento. Honestly, it just doesn't care what can stop it if it's removed what it needs to.
tl;dr - Duggy's just too good of a Pokemon in the current RU meta due to how many top threats are actually susceptible to it with a general ease of doing it's job. It's ability to hamper the viability of many of the top Pokemon by forcing players to play safe or not slipping up one move is fairly restricting, and it's a Pokemon that at this point should be banned from the tier.
