Don't ban
So, I've probably been one of the more outspoken anti-ban players, and I'm pretty most people know what my arguments are, so I'll just summarise my points. These are mostly to refute pro-ban arguments, which is pretty much what I need to do since the burden of proof should be with those arguing for a ban. Also, I'm going to address Shadow Tag and Mega Gengar at the same time since they follow very similar reasoning. So, the main arguments of the pro-ban camp are (minus the dumb arguments like "Mega Gengar makes stall cry"):
Mega Gengar (and Shadow Tag) removes the choice to switch:
Probably the argument most people are going with. I've highlighted why this does not make it uncompetitive and ban-worthy because while yes, it does remove your choice of switching for 1-2 turns (which is what I mostly experienced), this is not enough to invalidate every other choice that you've made in a game. In short, if someone beats you by using Shadow Tag to remove an important Pokemon and sweeping with its counter removed, that "choice of switching" in which you were denied was one turn in a larger scheme of a game. Just because you've got a key Pokemon trapped does not mean you've automatically lost the game. I think my post
here in response to Dice explains what I mean. Yes, Shadow Tag takes away your choice to switch for 1-2 turns and puts you at a great disadvantage because of it. However, just because it increases someone's chances of winning does not mean it is causative for that person's win. Plenty of things can happen (minus hax and choking) between a successful trapping from Mega Gengar and a successful execution of whatever strategy that Mega Gengar has made it easier for (secondary checks, getting outpredicted, counter-sweep, etc).
Also, just a smaller note, just because Mega Gengar has prevented the Pokemon from switching, does not mean it can actually get rid of whatever Pokemon that it's there to remove either. You still have Taunt/Destiny Bond 50/50s (which are no different from choosing your Ground or your Fairy against Zekrom, for example), Shed Shell on select Pokemon, VoltTurn/Baton Pass, Dragon Tail, or Pokemon that simply don't care (Ghosts, MMY, Deo-A, etc). This is not to mention that for the case of Mega Gengar, it needs to Mega evolve to even get Shadow Tag, and that one turn can be incredibly precious. If you team is used in a way that Gengar cannot even mega evolve without risk of getting killed, then it's pretty much a non-threat.
Mega Gengar creates 50/50s in switches because people are afraid to switch their important checks:
I'm outlined in depth why this argument is flawed. Basically, there is nothing fundamentally different between the 50/50s that Shadow Tag brings to the table and other 50/50s that occur in the game already, for example Specs Reshiram's Blue Flare vs Groudon - do you switch to your Steel/Fairy and get trashed by BLue Flare or do you switch in Palkia to get trashed by Draco Meteor. Fundamentally, there is no difference apart from the timing of the 50/50, since both 50/50s would yield a dead Pokemon if you chose the wrong switch. The other problem with the 50/50 argument is again, the fact that there is no causative relationship between that Shadow Tag 50/50 and the result of the game, even if the correlation is greater due to increased odds.
My thoughts:
I think the biggest problem with pro-ban arguments is that they are confusing what happens in a single (or multiple) turns and what happens overall in a game. If we compare with the rest of the other clauses that we've banned for being uncompetitive, a recurring theme is that what happens is because of the uncompetitive factor, things accumulate and
causatively influence the outcome of a game in the favour of the person using it. It's a bit hard to say in one sentence, but I'll explain what I mean. Also, luck is a big factor in pretty much every ban we've had, even though it is not the core issue of why we banned it. I'll basically go through the individual clauses (apart from Species) and explain why Shadow Tag is different:
OHKO Clause:
Basically a luck-centred ban. What the argument is that a "switch" to a counter can be rendered null because of a 30% chance that the Pokemon is killed. Again, it revolves around a coin flip. However, what I believe is the real uncompetitive part of OHKO Clause is that you can win a game purely on these coinflips. A Scarf Kyogre can waltz in and spam Sheer Cold and win the game just by doing that alone (trust me, I've seen it happen a few times). The fact that you can get a counter removed for another Pokemon by baiting in the counter and winning a 30/70 coinflip was not the thing that made OHKO truly broken. If it was just that one counter, it's a similar position to Shadow Tag. You can still go on without that counter. You cannot win, however, if you lady luck hated you and had Sheer Cold hit you too many times in which you were essentially "lucked out".
Moody/Swagger Clause:
Again, a luck-centred ban. It is the accumulation of multiple turns of luck that makes you lose a game, not just a Pokemon. See what the difference between this and Shadow Tag is? With Moody and Swagger, you lose because essentially you are playing with coinflips only, and therefore ALL decisions made in the game (or a large percentage) are rendered moot by luck, while Shadow Tag only restricts you to ONE decision (or maybe 2-3 or slightly more, but is nowhere near in the scale of Moody/Swagger).
(We used to have and we should still have) Evasion Clause: See Moody/Swagger
Sleep Clause:
Probably the one closest to Shadow Tag in the sense that it's not purely a luck ban. I still stand to reason that luck very much underlines a lot of why sleep is broken (see
here). It's a long tl;dr, but the main points are still again, 1) sleep has major elements (Sleep Talk is random, sleep counter is random, speed-ties and accuracy if you take away Sleep Talk and sleep counter), and 2) Sleep was strong because it could disable everything on your team. Unlike Shadow Tag which traps and usually removes 1 Pokemon a game, Sleep disables every Pokemon. So, Shadow Tag is focused, while sleep is more "global" in terms of a game. Again bring back to what I was talking about before, the difference is ST affects a few select turns and decisions, while Sleep affects all or a large majority of turns and decisions. THAT is what makes Sleep uncompetitive and what makes ST not.
Species Clause: Really don't know why we have Species Clause apart from the fact that make sure the game isn't weird af, but I can't see any competitive/uncompetitive reason
Endless Battle Clause: Like nuclear weapons, Endless Battle is kind of like a situation where no-one wins, and therefore that completely contradicts the meaning of the word "competitive"
Other things to bring up:
- Shadow Tag removing things is not something new at all. We have had trapping ever since gen 2, and it really took off in gen 4. However, there have been no problems with it since now. We had Magnet Pull/Arena Trap/Pursuit in OU/UU, and Wobbuffet in DPP was arguably even better at taking down threats than Mega Gengar or Gothitelle in XY because unlike Mega Gengar, it did not need to mega evolve, nor could you see that it was coming because there was no team preview. There may have been some whispers about wanting to ban Wobbuffet back in gen 4, but the overwhelming consensus was that it was not uncompetitive in gen 4. I know people are arguing that Mega Gengar is far more versatile than Wobbuffet back then, but in terms of actual ability to take down its threats and create opportunities for teammates, I really think that Wobbuffet was around the same level, if not better. If we didn't ban Wobbuffet back then, then I see no reason to ban Mega Gengar now.
- Reciprocity - you can also trap your opponent's key Pokemon with Shadow Tag. So, in the end, the one who actually executes his strategy first (ie the one who played better) is still the one who wins. I think that's still competitive. You might say that that would mean the game would revolve around Shadow Tag, and if that is the case, why does it matter? This is an overcentralisation argument, not one for "uncompetitive". The metagame revolves around Xerneas and Arceus and Kyogre and other threats. Why should Shadow Tag be treated differently?