Okay, so after some more tests, a lot of theory moning, and a long skype conversation, enigami, da, and myself came down to some sort of conclusions who seems alright for the rankings:
S = Dragonair / Drowzee / Gastly / Seadra
A = Ninetales / Seaking
B = Arbok / Electrode / Magmar / Poliwag / Vileplume / Wartortle
C = Graveler / Lickitung / Parasect / Primeape
D = Kabutops / Pidgeot
Explanations:
S = Top 3 stays there, Drowzee is added because there isn't any good reason not to use it really. Everything takes a lot of damage from its Psychics except... opposite Drowzee. It spreads both status, can run rest on some teams, is good early, mid, and end game. It definitely has what it takes to be on 100% of teams, and it should be
A = Seaking is here because even though it's not directly threatening, it's one of the most consistent mons. A lot of the other pokemon of the tier can sometimes lack a good match-up, a situation to get in, flexibility... Seaking can deal with a handful of situations, supporting your seadra and dealing damage to a whole bunch of pokemon thanks to Agility, it's the best mon to go double water etc... A thing to keep in mind is that there's a quite huge gap between S ranks and the rest, because most of the mons don't feel consistent. Seaking does.
Ninetales feels A worthy, because even if a couple of days ago we saw a lot of double water teams, it started to feel problematic due to mons like Electrode. You need to be able to check Electrode in your teams, which means using Vileplume/Parasect/Electrode/Graveler in your team. Less double water and more grass types makes the meta more opened to Tales, and btw it can switch into electrode decently, and into gastly comfortably. It also has some nice tools like Fire Spin and Confuse Ray to deal with a handful of situations. It feels more consistent than other mons
B = No changes for Arbok (tough to get in, but supports dnair very well), magmar (seems below Ninetales but has some nice advantages mainly psychic and physical power), poliwag (good with less double water), vileplume (.). Electrode raises to B because it has the potential to be very dangerous if unchecked, it's threatening to a lot of the tier, whether it's by damage or status. It can actually switch into Dragonair, and is only cockblocked by Graveler. You run a check to it on every team otherwise it can destroy it. It's also the only pokemon capable of checking both Seadra and Electrode. Wartortle raises to B. It's less consistent than Seaking (bulk/speed/agility) but Seismic Toss is an interesting move. The meta can be about freeze wars between seadras if you want to, or you can force seadra to rest to get in stuff (mons that set ups, or anything that deal damage in a particular situation). Also, being two ranks Seaking isn't right. It's less consistent, but not THAT less consistent.
C = No changes for Primeape (a bit difficult to teambuild around, needs a lot of conditions to work well, and predictions). Lickitung gets up, it doesn't rly have consistent counters, sleeping seadra is an easy way to get it in, it can switch into some stuff once. It can be a threatening mon, but it needs support and set up. Seems C worthy.
Parasect gives some good competition to Vileplume, notably on the offensive side. With access to SD and Growth, you can use it in a whole bunch of ways. it checks gastly compared to vileplume, with the possibility to paralyse it, beats vileplume etc It's a pretty good mon, it needs support because it's quite slow, but it provides some too.
Graveler was overlooked because of the water spam, but now Trode is in the picture. You have the electric ? You have the ground, it's how rby works after all. Compared to grass types, it actually hurts stuff on the switch, because nothing rly switches into it (parasect is ok but still 2HKOd by rslide). It also cockblocks other stuff like gastly (who considers mega drain on some grav weak teams) and pidgeot. Forces primeape to use submission and to drop a move... It has an influence on the meta, therefore C
D = Pidgeot, Gastly is everywhere, it can only hit it with Wing attack, which is poor. It's a pretty poor mon in general, graveler sees usage now, electrode too, the meta is v hostile to it overall. Kabutops seems to need too much support now. More and more mega drains, not a good match-up vs gastly (can only surf it on the switch which is prediction reliant), not a good match-up vs other waters, setting up is tough because gastly's here anyway, it just needs too much support.