@ganj4lf
I don't agree at all that Torn-T has a much wider range of safe switch-ins in comparison to Terrakion. For Torn-T there are Jirachi, Rotom-W, Rotom-H, Bronzong, Metagross, Zapdos and i thinks that's it. Heatran is not a safe switch in. It gets 2HKOed by Superpower if it is SpDefensive, and if offensive it can even be 2HKOed by Hurricane + Superpower. Chansey is a shitty switch-in, as Torn-T with Taunt murders it, and same goes for SpD Skarmory. Now let's see some switch-ins for Terrakion. Gliscor, Landorus-T, Hippowdon, BU Toxicroak, Mew, Slowbro. So Torn-T has 6 and Terrakion 6. Yeah i know that some of them can be argued, but 1 more or less doesn't make a lot of difference, and in the end of the day, they have more or less the same number of safe switch-ins.
But let's go further... What can revenge kill Terrakion and what Tornadus-T? As you can see in this case, Torn-T is way better, as it has superior Speed, and is not weak to Bullet Punch and Mach Punh, but is weak to Ice Shard, which is the less popular priority out of the three. Not to mention that Terrakion can be trapped by Dugtrio.
In rain, there is no doubt that Torn-T is one of the more threatening pokes in OU, and in my eyes is better than Terrakion, in rain again. The question is, is rain considered as a lot of support, or little support... If it is little support, then Torn-T fits in S rank, while if it isn't it goes to A rank. Imo Drizzle support is very easy to provide, and doesn't hinder your team at all, quite the opposite actually in many situations. So putting Politoed in your team to make Torn-T work to its fullest potential is not a lot of support. Many offensive pokemon need certain checks and counters eliminated, as well as entry hazards support, in order to succeed. Torn-T needs way less team support in those aspects (weakening of checks and counters) as it can weaken most of its counters and checks itself anyway, as all of them except Zapdos and Jirachi lack reliable recovery, and it is fucking immortal to problems that other offensive pokes face, hazards and LO recoil, meaning it can live long enough to outlast its check and counters that lack reliable recovery. Not to mention that Torn-T has so few checks and counters in the first place. So while Torn-T requires a bit more support than some other offensive pokes, it becomes way more threatening than most offensive pokes with this support, which as said again, is not too much of a deal anyway.
Torn-T for S tier.
As about Landorus-I and Ninetales i am really torn. While Ninetales offers godlike team support, it often struggles to stay alive. Dugtrio, SR and her shitty bulk all make sure of that. Ninetales is one of the few support pokes that needs a lot of support to work. You need a way to remove SR, a way to win weather wars, a way to deal with Dugtrio, and a way to bring her in in the first place, as she is quite frail. All of those problems prevent her from being an S rank poke, but she is definitely one of the best A rank pokes, as the support she offers is indeed exceptional, just not so easy to provide. You can't just fit Ninetales into a team and call it a day, but you can do this with Politoed, Tyranitar and Hippowdon. For this reasons Politoed is in the S rank. The sand inducers are not in S rank because Sand doesn't provide huge team support, but if it did, you can be sure that they would be S rank pokes. Having Politoed and Ninetales in the same rank just doesn't feel right, when the first one is clearly superior individually, and in terms of how easy it is for Poltitoed to offer the support. I am not saying that Rain outclasses Sun, i am saying that Politoed outclasses Ninetales as a weather inducer and as a standalone pokemon. Keep Ninetales in A rank.
EDIT: Removed bulky Starmie and added BU Toxicroak as safe switch-ins to Terrakion.