Ok, I feel I need to make a big post because there's been a lot of posts and ban proposals recently along the lines of "this meta's banlist differs from other metas, let's fix that" or "let's change this meta so that its balance is closer to that of standard tiers", which I honestly think is a big mistake. So rather than argue with every suggestion that inevitably pops up to replace the last, I'm going to take this opportunity to discuss 1v1 Tiering Philosophy instead.
The big thing about 1v1 is, well, you pick a pokemon and that's it. Being able to counter a set is the same as being able to check it. And while pokemon need to work well together to counter all the common sets you're likely to see, there isn't the same level of coherence between members of a team - from what I've found there's no such thing as running only stall pokes because it's more effective than running two stally mons and an offensive set. The reason all members of an OU team may follow the same playstyle is that otherwise momentum will be lost, different mons will need different amounts of support, and the team won't be greater than the sum of its parts. In 1v1, however, this is not the case.
So I'd argue that OU's reasons for banning or not banning a pokemon may well be different to those in 1v1, to the same extent as DOU having a different set of requirements. Because of this, I'd like to look at the very basic reasons for banning, and try to work out a coherent method to follow in 1v1 such that the right mons end up banned or not banned.
Let's start at the top: We don't want this to be AG 1v1. The idea of tiering is that we play with the common pokes, not the "hugely OP ones" such as m-ray or p-don that Game Freak seemingly designed to be OP, rather than the more standard mons. And if this isn't a good enough reason for you, my other two reasons are: a) having such powerful mons would likely decrease variety of viable pokemon and b) it simply wouldn't be as fun. The question, then, is where to draw the line in terms of what pokemon seem definitely broken, seem will definitely reduce the number and variety of viable pokemon and strategies, and will make the game less fun.
A good starting point might be OU's preliminary banlist or the Battle Spot bans, both of which are pretty similar. And to be honest, it's not that far from 1v1's current banlist. Aside from the blaziken ban and ignoring nintendo's bans (like mew or zygarde) that aren't based on competitive reasons, there aren't that many differences. Note I'm not necessarily saying this is a good place for the meta to be at - OU's certainly changed a lot and BSS starts with BS for a reason but from that point on, I'd argue there needs to be a clear and coherent reason in favour of a ban, rather than against.
So what's a good or bad reason for a pokemon to be banned? Bans exist such that a) the metagame is balanced and b) there are a wide variety of pokemon sets and strategies available while teambuilding. However, I've already explained that playstyles don't really happen as much in 1v1 - you might ban something in OU if it auto-bets any and all stall, but this isn't anywhere near as good a reason in 1v1 where running stall on two thirds of your team doesn't in any way restrict the other third. Just because a pokemon beats all stall mons doesn't mean you're limited in terms of available strategies, at least to a large extent. Moreover, there are a wide range of sets and strategies that are most certainly usable in the current metagame. Offensive sets such as choiced sets, setup sets, or simply powerful mons like Zard Y are definitely viable. Stally sets, such as Charm Chansey and even PP stall mons are certainly usable. Other kinds of sets such as subseed whimsicott or sub/encore/disable alakazam, while gimmicky, are still usable. Therefore, I'd argue that the only reason to ban a pokemon in the current metagame would be for balancing purposes.
So at what point is a pokemon broken? This is where definitions will always become a little fuzzy, however I honestly don't see that any of the current S-rank pokemon are broken. Every one of them has a wide range of available counters, whether it be Porygon-Z countered by Chansey or Mega Salamence losing to Iron Defense Deoxys-D.
So in summary, what I'm trying to say is that the meta is in a very good place right now. We simply don't need to shake it up in the way some of these changes would do, and in fact were we to design the metagame from scratch I'm pretty sure this is what we'd end up with in any case - after all, that's basically what I've just done.
There's just one change to the metagame that I'd recommend. Unban Blaziken.