When is a Rapid Spin user has no reliable Recovery and a mediocre match up against most Stealth rock users ever a good idea? Doubly so when the typing is garbage even OUTSIDE the rocks? And the point being made is that the entire appeal of Aurora Veil is getting both screens in ONE action. Sandslash adds an additional action to the chain, because rather than Ninetales -> Aurora, the sequence becomes Ninetales -> Sandslash -> Aurora Veil.
The reasoning you provide is that Slash can be a back up setter, but Ninetales isn't a mon that has nearly as hard a time setting Veil a second time, because it's natural speed is actually good and it sets its own Hail. Sandslash needs Ninetales to have been on the field recently enough for hail to be present, and then has to make it onto the field with enough threat to force out the thing it's veiling on. Whether or not Ninetales is "easy" or "hard" to set the Veil with, Sandslash is objectively more difficult and inefficient to do so, in particular because the stacking weaknesses mean that most of Ninetales' answers will probably deal with him about as well. Given how Aurora Veil works, if you get it set once, you should have a sweeper able to break so much of the opponent's team that they can't keep momentum away from a Ninetales re-entry after their team's half dead. His coverage is garbage, he gets Walled by Bulky Waters like Tapu Fini (who proceeds to remove your screens and your Rocks along with theirs), or Manaphy who proceeds to set up Tail Glow/Z-Rain Dance (or BOTH given this thing) in your face and then murders your team. It also can't hit non-grounded Steels like Celesteela, who Automotizes in your face, or throws out some Leech Seeds to stall out your Hail, Magearna can Shift Gear on you to reach Speed tie with Max/Max (outspeeds this variant here even in Hail) and Aura Sphere/Fleur Cannon through your bulky attackers. Sandslash also becomes set up fodder for BU Buzzwole, and Defensive Mega Venusaur can stall out with Synthesis EVEN UNDER HAIL, or just kill you
252 Atk Sandslash-Alola Icicle Crash vs. 248 HP / 96+ Def Thick Fat Venusaur-Mega: 84-98 (23.1 - 26.9%) -- guaranteed 4HKO after hail damage
0 SpA Venusaur-Mega Hidden Power Fire vs. 0 HP / 0 SpD Sandslash-Alola through Light Screen: 146-174 (50.1 - 59.7%) -- guaranteed 2HKO after Stealth Rock
This thing's damage is too pathetic to create chances for it to veil or to rapid spin hazards away, Ninetales gets away with it because it takes minimum conditional building, its speed tier is fast enough unaided to set up, Freeze Dry stops it from being totally passive shit against Tapu Fini or Pelipper, who are the best at removing/preventing its screens, and while not good, its typing still affords it a resistance or two that let it get the set up turn it needs for the Veil. Also, Encore is important for Ninetales because it doesn't have the power to break things, so it discourages setting up on it while it sets the Veil.
The entire appeal of Aurora Veil, as I said, is the speed of getting the two screens up so that a sweeper can get in and rampage. Suicide setters in previous gens were popular because they were an easy way to get them up early game once. Ninetales gets them up in fewer turns, and creates momentum almost as well by threatening Encore. Sandslash's set has you trying to give it more utility alongside Aurora Veil, when what a mon needs is options that FACILITATE Aurora Veil. That move is powerful enough to make an otherwise shit mon viable in Ninetales, and that's only because it has Snow Warning to completely ignore the obvious inhibition of the move. When you reach the point of needing another Aurora Veil setter, when the entire appeal is one mon being able to set both screens with it reliably, on its own, for others to sweep, then you're either not playing Aurora Veil well or against a team where you'll only fare worse for using Alolan Sandslash in any manner.
Alolan Sandslash is garbage in OU. Hell, Alolan Ninetales is garbage in OU for anything besides Aurora Veil, it just happens it's the one "good" user of a move that is very obviously stupid good. This discussion is maybe one step above the Merciless/Venoshock Toxapex I saw earlier.
Can we get back to discussing uses for Alolan Ninetales that prove relevant? What kind of sweepers do you think it pairs with well, offensive "blitzkreig" sweepers like DD M-Gyarados or Shift Gear Magearna, or bulky win conditions like BU Tapu Bulu/Buzzwole and Coil Zygarde? With the latter type, they're most at risk early when trying to accrue their boosts, so protection for those turns seems ideal, especially with Zygarde who can become nigh unkillable but lacks reliable recovery to support stacking multiple boosts until perhaps very late game.
The reasoning you provide is that Slash can be a back up setter, but Ninetales isn't a mon that has nearly as hard a time setting Veil a second time, because it's natural speed is actually good and it sets its own Hail. Sandslash needs Ninetales to have been on the field recently enough for hail to be present, and then has to make it onto the field with enough threat to force out the thing it's veiling on. Whether or not Ninetales is "easy" or "hard" to set the Veil with, Sandslash is objectively more difficult and inefficient to do so, in particular because the stacking weaknesses mean that most of Ninetales' answers will probably deal with him about as well. Given how Aurora Veil works, if you get it set once, you should have a sweeper able to break so much of the opponent's team that they can't keep momentum away from a Ninetales re-entry after their team's half dead. His coverage is garbage, he gets Walled by Bulky Waters like Tapu Fini (who proceeds to remove your screens and your Rocks along with theirs), or Manaphy who proceeds to set up Tail Glow/Z-Rain Dance (or BOTH given this thing) in your face and then murders your team. It also can't hit non-grounded Steels like Celesteela, who Automotizes in your face, or throws out some Leech Seeds to stall out your Hail, Magearna can Shift Gear on you to reach Speed tie with Max/Max (outspeeds this variant here even in Hail) and Aura Sphere/Fleur Cannon through your bulky attackers. Sandslash also becomes set up fodder for BU Buzzwole, and Defensive Mega Venusaur can stall out with Synthesis EVEN UNDER HAIL, or just kill you
252 Atk Sandslash-Alola Icicle Crash vs. 248 HP / 96+ Def Thick Fat Venusaur-Mega: 84-98 (23.1 - 26.9%) -- guaranteed 4HKO after hail damage
0 SpA Venusaur-Mega Hidden Power Fire vs. 0 HP / 0 SpD Sandslash-Alola through Light Screen: 146-174 (50.1 - 59.7%) -- guaranteed 2HKO after Stealth Rock
This thing's damage is too pathetic to create chances for it to veil or to rapid spin hazards away, Ninetales gets away with it because it takes minimum conditional building, its speed tier is fast enough unaided to set up, Freeze Dry stops it from being totally passive shit against Tapu Fini or Pelipper, who are the best at removing/preventing its screens, and while not good, its typing still affords it a resistance or two that let it get the set up turn it needs for the Veil. Also, Encore is important for Ninetales because it doesn't have the power to break things, so it discourages setting up on it while it sets the Veil.
The entire appeal of Aurora Veil, as I said, is the speed of getting the two screens up so that a sweeper can get in and rampage. Suicide setters in previous gens were popular because they were an easy way to get them up early game once. Ninetales gets them up in fewer turns, and creates momentum almost as well by threatening Encore. Sandslash's set has you trying to give it more utility alongside Aurora Veil, when what a mon needs is options that FACILITATE Aurora Veil. That move is powerful enough to make an otherwise shit mon viable in Ninetales, and that's only because it has Snow Warning to completely ignore the obvious inhibition of the move. When you reach the point of needing another Aurora Veil setter, when the entire appeal is one mon being able to set both screens with it reliably, on its own, for others to sweep, then you're either not playing Aurora Veil well or against a team where you'll only fare worse for using Alolan Sandslash in any manner.
Alolan Sandslash is garbage in OU. Hell, Alolan Ninetales is garbage in OU for anything besides Aurora Veil, it just happens it's the one "good" user of a move that is very obviously stupid good. This discussion is maybe one step above the Merciless/Venoshock Toxapex I saw earlier.
Can we get back to discussing uses for Alolan Ninetales that prove relevant? What kind of sweepers do you think it pairs with well, offensive "blitzkreig" sweepers like DD M-Gyarados or Shift Gear Magearna, or bulky win conditions like BU Tapu Bulu/Buzzwole and Coil Zygarde? With the latter type, they're most at risk early when trying to accrue their boosts, so protection for those turns seems ideal, especially with Zygarde who can become nigh unkillable but lacks reliable recovery to support stacking multiple boosts until perhaps very late game.