I nominate Wailord for C Rank (or at least D Rank), why?
1. It can make 101 HP substitutes, that's something for.
2. It's natural bulk is quite excelent, and it's offensive stats are usable, now if you put defensive EV's, you have a tank that can shoot quite decent Scalds to everything on the tier.
3. Add the fact that it can use Aqua Ring, it does have Pressure, and can use Subsitute + Protect, and you'll make almost a mimic of Walrein in the Hail... but without the need of weather, with a better defensive type, with access to STAB Scald, and with an almost identical natural bulk.
4. It can even Setup a Substitute facing a Magnezone 1+ using Thunderbolt (I tested and calculated already), I think that's a good demostration of how Wailord can setup Aqua Ring + Substitute against almost anything on NU (and you can even make him only to tank physical or special attacks, but it can actually tank both quite well).
5. Once Wailord had Aqua Ring and Substitute setted, you can only phaze him with Roar/Whirlind or with Taunt, because it's subs resist even 2 STAB Bullet Seeds coming from 80 base attack, and even if you try to phaze it Wailord still had STAB Scald coming from 90 base special attack, and that gives a good punch, and if you success on burning, you can tank it's physical attacks like a king, or stall it's HP and PP to the oblivion.
6. If we take Pressure in account, it can drain a huge total of 64 of PP from differents attacks, as we know, even Pokémon with moves with high PP will have all their offensive drained by Wailord, and if they try to stall it with not-attack moves, you can just Scald them until burning them and keep overstalling, or just K.O things by doing damage, or by summing Toxic damage from Toxic Spikes.
If it doesn't seens like a huge offensive tank, you can focus it's defense on only one area, and you can use Hydro Pump or Surf with 252 EV's on SPA to hit really hard while you're still having a (huge) bulky of one side, and more speed than the most of the walls of the tier. It also does have an offensive set using Choice Scarf and Water Spout, and it hits really hard and is a good revenge killer, generally, and can act as a good late-game cleanner, too, and at the difference of other special late-game cleanners, Wailord can do decents Double-Edges (bypassing special walls and others waters) and almost losing nothing of it's huge HP, and thus, not losing too much power from Water Spout.
Brine can also be used on Cleanners Sets and on the main set I said as long you have Toxic Spikes support, so, you can finish of with a STRONG STAB of 130 a good number of threats with wasting only few PP's of substitute + protect.