Here's a little team I threw together after seeing one too many attempts at Hail Stall teams for standard end up just being worse than ObiStall. I realized that what Hail Teams needed were not your standard "set up entry hazards until your opponent dies", but rather Pokemon who could take advantage of the residual damage that almost nothing resisted. It could still use a little work, but I've got maybe a 70-80% win record in my handful of test games to see if the premise is even sound. So, without further ado, here's my team.
The Lead:
Celebi @ Choice Specs
Timid / 4 HP / 252 SpA / 252 Speed
Ability: Natural Cure
Leaf Storm
Earth Power
Stealth Rock
Trick
This is a little set I cooked up when I realized a few things: No one knows how to react to Celebi as a lead, Celebi has both Stealth Rock and Trick, making it a fairly ideal lead, and Specs Celebi is capable of taking out other Auto-weather Pokemon, who may not switch out because they don't know what to expect.
Specs Leaf Storm does enough to OHKO Standard Hippowdon and then some.
Specs Leaf Storm has enough to get a clean OHKO on CB Tyranitar and anything less bulky. It only manages a 2HKO on 240/184 Tyranitar, the set listed under the analysis as "Lead Tar", but he probably runs Sash anyways, and hasn't been all too common, to my recollection.
Against slower leads like Bronzong, Trick locks them in to Rocks and gives you a turn on their switch to set up rocks of your own. Swampert clearly dies to Leaf Storm. This also works against leads you expect to Set up
Azelf and Aerodactyl can be 2HKO'd by Leaf Storm, and if they waste their first turn taunting you, all they do is get Rocks up. Maybe not ideal, but it's better than eating Azelf's Flamethrower/Explosion. If Azelf Rocks on the first turn, I switch to Heatran to absorb the incoming Flamethrower/Explosion. As for Aero, the best he can do to Celebi is the rare Ice Fang or a Rock Slide/Stone Edge, so staying in and finishing him off should be no problem.
Earth Power OHKO's Heatran who lack Occa Berry, but only manages 74-88% if he has the Berry, making it a risky proposition as his Fire Attack clearly spells danger for you. Earth Power has a chance of OHKOing Metagross who lack Occa Berry.
The increasingly commong Mamo lead hits you pretty hard with Ice Shard if he uses it, but he will die to Leaf Storm either way (unless he runs sash).
Against Jirachi, he's tried to Trick me every time I've seen him, so I've merely set up Rocks and then switched out as he was forced to as well.
I need a little help with the EV Spread and Nature, this was a fairly arbitrary Choice. I'm thinking Modest is probably better, as it makes the OHKO on Metagross more of a sure thing and I believe gives a chance to KO the bulkier Ttar spreads. I'm also thinking some speed can be dropped in to HP/Def/SpDef, but I'm not sure how much and into which. I'm thinking enough to outrun Positive Heatran (172 Speed EVs) and sticking the extra 80 (plus the 4 currently in HP) into Def, but I'm interested to see what Smogon thinks.
The Firewall
Heatran @ Leftovers
Modest / 252 HP / 16 SpA / 240 SpD
Ability: Flash Fire
Overheat
Earth Power
Will-o-Wisp
Roar
Anyone who's played my other team knows I'm a fan of Burn Support Heatran (my other team uses a variant as my lead). This is me trying another variation of him as the much-needed fire absorber for this team. Overheat is his most powerful move and can dish out a lot of damage. Earth Power is primarily for opposing Heatrans, who hilariously fail to KO in return with their own Earth Power unless Specs'd. Will-o-Wisp cripples many common Heatran switch-ins, like Gyarados, Salamence, and Tyranitar. And Roar can be used to rack up Stealth Rock/Hail damage and scout their team, as well as provide an answer to pesky Curse/CMers, particularly Latias, Snorlax, and Suicune, who think they have a free pass to set up on Heatran.
Teams up nicely with Celebi for the standard "CeleTran" combo of resists.
The Hail Mary
Abomasnow @ Leftovers
Adamant / 252 HP / 156 Attack / 100 SpD
Ability: Snow Warning
Ice Shard
Wood Hammer
Substitute
Leech Seed
Abomasnow is primarily here to set up residual damage that few opponents resist, eliminating Leftovers and wearing down Pokemon, so as to open up a sweep. Ice Shard provides good insurance against Salamence and Flygon, while Wood Hammer takes care of pesky Bulky Waters. SubSeed is good against Stall Teams, as it can wear down annoying Pokemon like Cresselia and Blissey.
The Net
Rotom-f @ Choice Scarf
Timid / 4 HP / 252 SpA / 252 Speed
Ability: Levitate
Blizzard
Discharge
HP Fire
Trick
Anyone who's ever seen me rate a team knows I pretty much always suggest Scarf Rotom to shore up weaknesses to common Pokemon. I usually suggest Rotom-H, but Rotom-F works just as well against many of the threats (only slightly worse against Lucario, but I can deal) while packing a devastatingly powerful Blizzard in the Hail. Provides one of the best checks in the game to DD Gyarados, SD Lucario (still a good counter if he lacks Crunch), and any form of Scizor. Also provides a much-needed fighting immunity and appreciated immunities to ground and normal.
The Mop
Mamoswine @ Life Orb
Naughty / 252 Attack / 236 Speed / 20 SpA
Ability: Snow Cloak
Earthquake
Ice Shard
Stone Edge
Blizzard
So many teams are weak to MixMamo, it's not even funny. Pretty much any team without Levitate Bronzong or CB Scizor, actually, gets most of its members swept by this beast. And even against teams with those members, if they are taken out or they slip up to a nice Snow Cloak hax, Mamoswine does a phenomenal job of tromping over the remainder.
The Broom
Lucario @ Life Orb
Adamant / 252 Attack / 4 Def / 252 Speed
Ability: Inner Focus
Close Combat
ExtremeSpeed
Stone Edge
Swords Dance
This is my most flexible member, if you want to suggest a replacement, I'm all ears. Basically, the idea is that once their team has succumbed to the residual damage of Stealth Rock and Hail, they will be ripe for the picking off by Lucario. He also provides a much-needed resist to Rock, so replacement member suggestions should keep that in mind.
At a Glance






The Lead:

Celebi @ Choice Specs
Timid / 4 HP / 252 SpA / 252 Speed
Ability: Natural Cure
Leaf Storm
Earth Power
Stealth Rock
Trick
This is a little set I cooked up when I realized a few things: No one knows how to react to Celebi as a lead, Celebi has both Stealth Rock and Trick, making it a fairly ideal lead, and Specs Celebi is capable of taking out other Auto-weather Pokemon, who may not switch out because they don't know what to expect.
Specs Leaf Storm does enough to OHKO Standard Hippowdon and then some.
Specs Leaf Storm has enough to get a clean OHKO on CB Tyranitar and anything less bulky. It only manages a 2HKO on 240/184 Tyranitar, the set listed under the analysis as "Lead Tar", but he probably runs Sash anyways, and hasn't been all too common, to my recollection.
Against slower leads like Bronzong, Trick locks them in to Rocks and gives you a turn on their switch to set up rocks of your own. Swampert clearly dies to Leaf Storm. This also works against leads you expect to Set up
Azelf and Aerodactyl can be 2HKO'd by Leaf Storm, and if they waste their first turn taunting you, all they do is get Rocks up. Maybe not ideal, but it's better than eating Azelf's Flamethrower/Explosion. If Azelf Rocks on the first turn, I switch to Heatran to absorb the incoming Flamethrower/Explosion. As for Aero, the best he can do to Celebi is the rare Ice Fang or a Rock Slide/Stone Edge, so staying in and finishing him off should be no problem.
Earth Power OHKO's Heatran who lack Occa Berry, but only manages 74-88% if he has the Berry, making it a risky proposition as his Fire Attack clearly spells danger for you. Earth Power has a chance of OHKOing Metagross who lack Occa Berry.
The increasingly commong Mamo lead hits you pretty hard with Ice Shard if he uses it, but he will die to Leaf Storm either way (unless he runs sash).
Against Jirachi, he's tried to Trick me every time I've seen him, so I've merely set up Rocks and then switched out as he was forced to as well.
I need a little help with the EV Spread and Nature, this was a fairly arbitrary Choice. I'm thinking Modest is probably better, as it makes the OHKO on Metagross more of a sure thing and I believe gives a chance to KO the bulkier Ttar spreads. I'm also thinking some speed can be dropped in to HP/Def/SpDef, but I'm not sure how much and into which. I'm thinking enough to outrun Positive Heatran (172 Speed EVs) and sticking the extra 80 (plus the 4 currently in HP) into Def, but I'm interested to see what Smogon thinks.
The Firewall

Heatran @ Leftovers
Modest / 252 HP / 16 SpA / 240 SpD
Ability: Flash Fire
Overheat
Earth Power
Will-o-Wisp
Roar
Anyone who's played my other team knows I'm a fan of Burn Support Heatran (my other team uses a variant as my lead). This is me trying another variation of him as the much-needed fire absorber for this team. Overheat is his most powerful move and can dish out a lot of damage. Earth Power is primarily for opposing Heatrans, who hilariously fail to KO in return with their own Earth Power unless Specs'd. Will-o-Wisp cripples many common Heatran switch-ins, like Gyarados, Salamence, and Tyranitar. And Roar can be used to rack up Stealth Rock/Hail damage and scout their team, as well as provide an answer to pesky Curse/CMers, particularly Latias, Snorlax, and Suicune, who think they have a free pass to set up on Heatran.
Teams up nicely with Celebi for the standard "CeleTran" combo of resists.
The Hail Mary

Abomasnow @ Leftovers
Adamant / 252 HP / 156 Attack / 100 SpD
Ability: Snow Warning
Ice Shard
Wood Hammer
Substitute
Leech Seed
Abomasnow is primarily here to set up residual damage that few opponents resist, eliminating Leftovers and wearing down Pokemon, so as to open up a sweep. Ice Shard provides good insurance against Salamence and Flygon, while Wood Hammer takes care of pesky Bulky Waters. SubSeed is good against Stall Teams, as it can wear down annoying Pokemon like Cresselia and Blissey.
The Net

Rotom-f @ Choice Scarf
Timid / 4 HP / 252 SpA / 252 Speed
Ability: Levitate
Blizzard
Discharge
HP Fire
Trick
Anyone who's ever seen me rate a team knows I pretty much always suggest Scarf Rotom to shore up weaknesses to common Pokemon. I usually suggest Rotom-H, but Rotom-F works just as well against many of the threats (only slightly worse against Lucario, but I can deal) while packing a devastatingly powerful Blizzard in the Hail. Provides one of the best checks in the game to DD Gyarados, SD Lucario (still a good counter if he lacks Crunch), and any form of Scizor. Also provides a much-needed fighting immunity and appreciated immunities to ground and normal.
The Mop

Mamoswine @ Life Orb
Naughty / 252 Attack / 236 Speed / 20 SpA
Ability: Snow Cloak
Earthquake
Ice Shard
Stone Edge
Blizzard
So many teams are weak to MixMamo, it's not even funny. Pretty much any team without Levitate Bronzong or CB Scizor, actually, gets most of its members swept by this beast. And even against teams with those members, if they are taken out or they slip up to a nice Snow Cloak hax, Mamoswine does a phenomenal job of tromping over the remainder.
The Broom

Lucario @ Life Orb
Adamant / 252 Attack / 4 Def / 252 Speed
Ability: Inner Focus
Close Combat
ExtremeSpeed
Stone Edge
Swords Dance
This is my most flexible member, if you want to suggest a replacement, I'm all ears. Basically, the idea is that once their team has succumbed to the residual damage of Stealth Rock and Hail, they will be ripe for the picking off by Lucario. He also provides a much-needed resist to Rock, so replacement member suggestions should keep that in mind.