Let's not get carried away with the Hail hype. Any mon that relies on Hail as heavily as Glaceon and Walrein do is requiring a huge amount of team support. Snover is much worse than things like Smeargle or Dual Screens Uxie who provide similar levels of support, but in a way that is useful to any Pokemon, not just Ice-types. Remember that last time Hail was allowed in RU, Snover didn't even have enough usage to stay out of NU. Hail is not a common battle condition, it's a huge support burden, and you should be factoring that into the rankings. I think that every dedicated Hail mon should be 2 ranks below its performance due to how much support it needs. On that note, I'd put Glaceon in B or C, Rotom-F in B or C, and Walrein in C or D. Glaceon is excellent in hail but pretty bad out of it. Rotom-F is not quite as good as Glaceon in hail, but it's still a reasonably useful mon even without hail. Stallrein has always been overrated; even if we assumed hail was free I wouldn't put it higher than B, but it is 100% reliant on hail to not be a wasted teamslot, so C or D is where it belongs.
Let's not start putting every hail mon in A and B please when they require more dedicated support than things like Linoone, Scyther, and Swellow.