OK, from reading through these posts I've found 5 major points that keep coming up as an argument for an Arena Trap ban, I've got to say I now have a solid stance on the issue.
BAN
1.
Dugtrio essentially guarantees one kill, with very little skill involved. Although this in itself is not the major issue, the fact is that with the trapping a player can essentially pick and choose one mon of their opponents to remove, which as
BeardyBennett mentions allows your opponent to remove your obvious wincon, when they only lose Dugtrio (
maybe) after he has done his job.
2.
Dugtrio forces other mons to run sets/items that are suboptimal in literally every other situation. Yep,
Shed Shell, the only other situation I've ever seen this used effectively is on Skarmory against Magnezone, but Skarmory isn't grounded anyway. Tapu Lele, Hoopa-U, and pretty much any stallbreaker are forced to run Shed Shell, which limits their effectiveness in all other situations.
3.
Dugtrio is broken on a large number of archetypes, the main problem being stall. Dugtrio is incredibly effective at what it does on any kind of team, the reason people bring up stall as the number one issue is that
the archetype as a whole is broken with the presence of Dugtrio. Again his effectiveness at removing stall/wallbreakers means that every stall team has to have Dugtrio or they are playing at a huge disadvantage to other stall teams, not to mention the fact that Dugtrio is also an answer to Chansey, Toxapex and Clefable (to name a few).
4.
Arena Trap is just Shadow Tag by another name. I know they are not exactly the same but if we look back at the reasons Shadow Tag was banned in the first place a lot of these reasons can be applied to Arena Trap and not affecting non-grounded pokemon is not enough of a counter, as this makes up such a small portion of OU.
5.
Dugtio buff, Groundium-Z and Baton Pass banned. I think these 3 factors are the major reason that Dugtrio has slipped under the radar until this Gen, his attack boost combined with his Nuclear option in Groundium-Z further backs up the point that he guarantees one kill for players with even the least amount of skill. To a lesser extent, I believe the removal of another escape option in Baton Pass has also aggravated the situation.
But, this isn't an argument on whether to ban Dugtrio, Arena Trap is being suspect tested. The point that a pokemon with mediocre stats is so powerful only because of its ability is surely more of a ban argument than a counter point?