Alright, so I'd like to elaborate on some of arguments, because I realised I sounded pretty anti-stall, anti-defence, and after actually playing this style of team on the ladder, one that benefitted from Landorus I being gone, this hasn't changed. What I aim to do here is to briefly go over some arguments that I don't agree with.
1) Lack of "true" counters
This is actually true, Landorus I can run over usual switch ins with unusual moves, but I don't agree that this is unhealthy at all. In theory, you can't switch in anything other than Mega Latias or Cress, but this isn't true in practice. Different sets have different switch-ins, but they all have some, so basically if you want to totally null a powerful breaker, you have to dedicate more than 1 teamslot to it. A lack of switch ins is just a breaker doing its job well, and it is balanced provided it isn't constantly getting free switch-in opportunities, and it has an abundance of things that can revenge kill it, these are both true of Landorus I. You can compare it to Hydreigon last gen, with a lack of switch-ins, but an abundance of checks, it was perfectly fine. As speed stats keep increasing, now 101 base is not that good.
2) This fact means that it heavily pressures defensive teams, and heavily limits their building options. Without this pokemon, new cores become available.
Yeah, I'm not actually going to argue with this point, but say that it is the job of a breaker to heavily limit the building options of a team that tries to have switch-ins for everything. If it didn't, it wouldn't be a very good breaker.
3) It differentiates itself from other breakers by having several advantages. It doesn't take up a mega slot, take life orb recoil, or spike damage. It is also very effective against offence.
Well, I agree that Landorus I is a highly splashable, very cost effective mon, but that's just the meta we're dealing with here, it isn't the only one. It's not like it can just run through entire teams by itself, or if it can, then the team isn't built very well. Fine, it isn't weak to rocks, and it doesn't wear itself down with a life orb, but you could also point out that other breakers in the tier have advantages over it that may cause you to pick them over it. RD Manaphy has an immunity to status, Charizard Y has recovery and hits harder, Gengar, while it might not hit as hard as the others, it does have few switch-ins, and is faster.
As for it being effective against offence too, that's correct, it is decent. I'm not going to buy the idea that it should be banned because it wrecks a variety of playstyles though. It doesn't limit the building of an offence team that much at all when compared to other threats in the tier, like Lopunny, Zard X, or Altaria. There is a specific type of passive team for which Landorus exerts one of the greatest pressure out of any pokemon in the tier, it's not stagnating the meta at all by forcing a certain style of building, there are plenty of other options besides a passive team.
4) You can still break through defence with certain mons, even without full stall having to prepare for Landorus I
I can, now it requires more specialisation because now they can prepare for more stuff, but this isn't even an argument as to why it should be banned. Fat balance and stall cores were already pretty common on the ladder, even if they did become more common in the suspect ladder. If it invalidated an entire play style, that would be different, and I would be pro-ban. I mentioned in the last paragraph how there are other options than passive teams, you don't have to use them, but even with Landorus I, you can use them. In a metagame with Landorus I, there can still be offensive, balanced, and bulkier teams, so it doesn't hurt variety more than any other prominent pokemon.
5) It can sweep once you remove its checks
Yes, it can.
I'll say a little bit more. If Latias is your one check to Landorus, and you are aware that it gets pursuit trapped by a very common team mate, then that's not very good building. Not to say Latias doesn't work, but that you should also have something like a Band Azumarill, a Talonflame, or a Rotom-Wash. It isn't alone in being a pokemon that requires more than one check, either.
Essentially, I'm not denying that Landorus is a very good pokemon. It can be put on to a lot of teams, though not without a complete lack of thought like Aegislash, and varies from decent to very effective against different play styles. However, it does not polarise the meta by completely eliminating a certain team model, it does not sweep through teams with one turn of set up, and it is not unique in being a pokemon with very few switch-ins that can punish free turns. Landorus has a strong impact on the meta, it does not define it, so really, I think it belongs in S rank and not on the banlist.
1) Lack of "true" counters
This is actually true, Landorus I can run over usual switch ins with unusual moves, but I don't agree that this is unhealthy at all. In theory, you can't switch in anything other than Mega Latias or Cress, but this isn't true in practice. Different sets have different switch-ins, but they all have some, so basically if you want to totally null a powerful breaker, you have to dedicate more than 1 teamslot to it. A lack of switch ins is just a breaker doing its job well, and it is balanced provided it isn't constantly getting free switch-in opportunities, and it has an abundance of things that can revenge kill it, these are both true of Landorus I. You can compare it to Hydreigon last gen, with a lack of switch-ins, but an abundance of checks, it was perfectly fine. As speed stats keep increasing, now 101 base is not that good.
2) This fact means that it heavily pressures defensive teams, and heavily limits their building options. Without this pokemon, new cores become available.
Yeah, I'm not actually going to argue with this point, but say that it is the job of a breaker to heavily limit the building options of a team that tries to have switch-ins for everything. If it didn't, it wouldn't be a very good breaker.
3) It differentiates itself from other breakers by having several advantages. It doesn't take up a mega slot, take life orb recoil, or spike damage. It is also very effective against offence.
Well, I agree that Landorus I is a highly splashable, very cost effective mon, but that's just the meta we're dealing with here, it isn't the only one. It's not like it can just run through entire teams by itself, or if it can, then the team isn't built very well. Fine, it isn't weak to rocks, and it doesn't wear itself down with a life orb, but you could also point out that other breakers in the tier have advantages over it that may cause you to pick them over it. RD Manaphy has an immunity to status, Charizard Y has recovery and hits harder, Gengar, while it might not hit as hard as the others, it does have few switch-ins, and is faster.
As for it being effective against offence too, that's correct, it is decent. I'm not going to buy the idea that it should be banned because it wrecks a variety of playstyles though. It doesn't limit the building of an offence team that much at all when compared to other threats in the tier, like Lopunny, Zard X, or Altaria. There is a specific type of passive team for which Landorus exerts one of the greatest pressure out of any pokemon in the tier, it's not stagnating the meta at all by forcing a certain style of building, there are plenty of other options besides a passive team.
4) You can still break through defence with certain mons, even without full stall having to prepare for Landorus I
I can, now it requires more specialisation because now they can prepare for more stuff, but this isn't even an argument as to why it should be banned. Fat balance and stall cores were already pretty common on the ladder, even if they did become more common in the suspect ladder. If it invalidated an entire play style, that would be different, and I would be pro-ban. I mentioned in the last paragraph how there are other options than passive teams, you don't have to use them, but even with Landorus I, you can use them. In a metagame with Landorus I, there can still be offensive, balanced, and bulkier teams, so it doesn't hurt variety more than any other prominent pokemon.
5) It can sweep once you remove its checks
Yes, it can.
I'll say a little bit more. If Latias is your one check to Landorus, and you are aware that it gets pursuit trapped by a very common team mate, then that's not very good building. Not to say Latias doesn't work, but that you should also have something like a Band Azumarill, a Talonflame, or a Rotom-Wash. It isn't alone in being a pokemon that requires more than one check, either.
Essentially, I'm not denying that Landorus is a very good pokemon. It can be put on to a lot of teams, though not without a complete lack of thought like Aegislash, and varies from decent to very effective against different play styles. However, it does not polarise the meta by completely eliminating a certain team model, it does not sweep through teams with one turn of set up, and it is not unique in being a pokemon with very few switch-ins that can punish free turns. Landorus has a strong impact on the meta, it does not define it, so really, I think it belongs in S rank and not on the banlist.