First of all, I want to say that I do not think that level 1 and 2 things should be banned from 1v1. (this argument mainly directed to
ganesha27) They are not hard to counter at all, and around the 1400s or so on the ladder, you don't even need to consider them when making a team because so many of the common sets nearer to the top of the ladder beat it. Charizard X/Y (with Will-o-wisp), Mold Breaker (Gyarados-Mega and Haxorus, among others), and Teravolt (Kyu-B) are common enough that level 1 FEAR things all lose to many other things on the ladder, so you won't see them very much. Also, things that are Steel type like Mawile and Aegislash (and Specs Steelix
Thisisafake name) pretty much wall these Sturdy abusers because they can't be poisoned. Alternatively, you could Trick or Switcheroo them a Choice item, locking them into Toxic/Endeavor, depending on which set you are facing. Or just Knock Off their Berry Juice.
However, I believe that
focus sashes should not be unbanned. This is all just me theorymonning because I've never played when they weren't banned, but I'm going to try to address all of the arguments presented.
In response to the Charizard/Greninja thing: These pokemon are really strong, obviously. They hardly take any skill to use and just destroy what's in their path. However, they are not without checks. Charizard always loses to Kyurem Black, and Greninja always loses to Chansey/Blissey. Now I understand these are very specific counters, but they are also very common in the current metagame. Chansey/Blissey is the reason the top of the ladder has practically no special attackers (especially Charizard Y), and Kyurem Black is a check to many common threats not named Mawile. Also, since I've started playing 1v1, I've noticed that the game is more or less rock-paper-scissors in terms of what you get put up against, because if you're using Mawile and you get put up against Kyurem Black, you win. However, if you're using Mawile, and you get put up against Entei/Charizard, it's an instant lose pretty much. The best way that I've found to ladder is you play 10 games with a certain set, and after that you analyze what you saw, and switch to a set that beats most of them.
Focus Sashes are not going to fix this Rock/Paper/Scissors style play, and if anything, make it more like this.
One more thing about Greninja: It could easily run Water Shuriken to get through these sashes, making them no less broken than before.
Focus Sashes are like Sturdy as an item, meaning you can have another ability in addition to a pseudo-Sturdy.
I know I'm theorymonning, and that's why I propose we test this. However, I don't think we should test it on the main ladder, as that could affect a lot of people's scores as they adapt to the new metagame. I believe that, in the style of OU suspect tests, there should be a separate ladder for 1v1 with Sashes, temporarily.
Just my 2 cents.