TCTphantom
formerly MX42
I can understand your viewpoint, yet I completely disagree.I'm not a great player nor experienced in RU, so this isn't exactly a balance viewpoint, but I personally think having only 1 perma-weather user in any tier is a bad thing, regardless of how good or bad that weather is. Either a tier should have all 4 weathers like OU, or no auto-weather at all in my opinion.
The reason for this is simply because there is zero strategy or difficulty in keeping up your weather up if there is nothing else to change it. The hail user just has to send out snover on turn 1 and hail will be up for the rest of the match, unless you carry a manual weather-starter which is not only rare but not a very satisfactory counter anyway - it requires you to use up a valuable moveslot (and possibly an item slot if you want to run a duration boosting rock), switch in the pokemon safely and then be a sitting duck for a second turn while you use the sunny day/rain dance/sandstorm. The opponent has 2 separate turns to either kill you, taunt you, set up on you or just do crippling damage so your mon can't switch in and continue to do its job effectively for the rest of the match. And if that wasn't bad enough, even if you successfully get the weather move off, snover can switch back in and instantly hail is permanently back, and you don't have a single turn to prevent this.
Sure, the hail user has to use up a teamslot for the shitty mon that is snover so it might well be theoretically balanced, but I personally hate strategies where you just have to sit back and take it. As much as I hate the omnipresent weather wars of OU, I find playing weatherless vs perma-weather of any kind to be far more unpleasant.
Also, I've played against stallrein a few times and I have never experienced such a potent combination of mind-numbing boredom and acute, hair-pulling frustration. It is seriously the least fun thing to face in the whole of pokemon, other than maybe sub/swagger liepard which is annoying for more luck based reasons.
So that's my take on this.
For starters, Sunny Day and Rain Dance teams are perfectly viable. One use of the move and you force Snover out (Snover never runs hail), forcing it to take crucial SR damage and break its sash. Not to mention, it's easy to give either move to a wall and just stop hail cold, once Snover is down and you are in safely. If your team is hail weak, you run a hail counter, as you would vs any Pokemon or play style. Not too mention, hail offense is not too powerful, as most threats are super weak physically, and a good fighter can easily Sweep them, most notably Gallade. Fire types also wreck hail, like Entei. Also, several pokemon have barren move sets yet can work great vs Hail, like Rain Dance Kabutops and Sunny Day Entei...
Also, you point out the frustration of Stallrein. An ice body + snow warning ban ruins this play style, while leaving other hail teams viable. In a meta sense