K so this team is at a glance instantly recognizable as a Hail Stall team. It incorporates the standard elements one sees on these types of teams: Snover, Toxic Spikes support, spinner, and a SubTect mon. The goal is to bring down an opponent slowly through Toxic Stalling and residual damage.
Now the Snover set used here is the optimal one for Hail teams, generally leading off and making up for its bad bulk by using Sash to notch hits on annoyances to Hail, especially on mons that do not have recovery. As Snover is so important due to bringing Hail itself, this is a given. I do wonder why the Rash nature is used over Mild, considering that Snover can actually take mons like pivot Slowking due to its typing and the fact that pivot Slowking is weak and doesn't run much coverage. This is keeping in mind that almost all priority destroys Snover. I also note the nice usage of Hidden Power Fire, which is really unsurpassed as a Hidden Power due to the ease it takes out certain Hail threats, especially Escavalier. The choice of Giga Drain over Wood Hammer is most certainly due to this being a stall team, and thus Snover is better off being kept than getting killed quickly and being caught off guard by a manual weather move. Now, every Hail Stall team needs Toxic Spikes support, and Molk's setter of choice is Qwilfish, a very useful mon on Hail teams due to a few aspects. Qwilfish has access to both Spikes and Toxic Spikes, which gives it multiple options, and has Taunt, which is immensely useful against set-up sweepers that try to pull moves on this team or defensive mons trying to heal, while stopping hazards to keep the mons in good shape. The speed creep aids this so it can shut down set-up sweepers before they can move. The main draw of Qwilfish over other mons with Toxic Spikes or Spikes, however, is its typing, which lets it shut down most physical Fighting types with the combination of Intimidate + Poison typing, and it can wall one of Hail's biggest threats, Escavalier.
Torterra is the other side of the hazards core, and this mon is very unique. Hail is rarely seen with this mon, and this is really the tech mon Molk has here. People tend to underestimate what Torterra's bulk and what it is capable of, and this Specially Defensive set puts everything Torterra has to good use. Due to its special typing, Torterra is able to completely shut down Specially Defensive Magneton, the true counter to the infamous Stallrein, so thus Torterra eliminates a huge counter for its teammate. As it is thoroughly unexpected, this works even better in play due to being immensely underrated. Torterra does not just set up vital Stealth Rocks and shut down the aforementioned Magneton set, but it also does well against Rotom-C, which would otherwise be able to Volt Switch all over this team. Although it can't do much back, the defensive investment permits it to take the common Scarf Leaf Storm well. Leech Seed is the final move option, and it does good work on a Hail Stall team, adding residual damage to the opposing mon and providing valuable healing for Molk's own mons, such as Qwilfish. Torterra forms a strong synergetical core with Qwilfish, as well as in their roles, majorly due to the fact both carry the vital hazards and each take on several of the major threats to this team.
Considering we have so many hazards at this point, and that this is stall, a spinblocker is a must. The spinblocker of choice here is arguably the best for stall teams: Spiritomb. Spiritomb boasts multiple advantages over other bulky ghosts, and several of these are, but not limited to, having access to Foul Play and having no weaknesses. For this team, Spiritomb walls most Fighting types who can pass Qwilfish, due to them struggling to have a move that hits Spiritomb for much damage. The biggest of these Fighting types is Gallade, which can wreak major havoc on this team otherwise. Tomb uses the excellent Foul Play to dole out the hurt on physical attackers and Psychic mons, while employing RestTalk to be able to be a defensive behemoth consistently through the game. The EV set chosen here is a Specially Defensive set, which deals with problems on that side of the spectrum better, especially Moltres. Due to this choice Will-o-Wisp is very vital to minimize the physical damage, because Molk's defensive backbone is more focused onto the Special side of the spectrum (eg Torterra, Spiritomb, Walrein, and Cryogonal being specially based.) Obviously the main goal of Spiritomb, however, is still to spinblock, and it can do this handily, defeating most spinners easily.
With these hazard weak mons, and to keep Walrein as effective as it is, the team uses Cryogonal as spinner. Bulky Cryogonal is a good spinner for Hail Stall mostly because it is the bulkiest of the main spinners, and it helps out a lot on the special side. The main move to see on this relatively standard set is the Haze. Haze is absolutely huge for this team to deal with set-up mons that are getting out of hand, especially something like CM Sigi. The set is quite standard, considering the lack of other options, although Blizzard over Ice Beam shows that Molk wants this to hit with some degree of power, therefore risking the lower PP, even on a stall team.
The star of the show is Walrein, more appropriately called Stallrein. This mon has been the bane of many a team's existence, and is now arguably the most broken mon in RU. We can see here Molk decided to go with the Special EV spread to set up on stuff like Moltres. Now, the moveset choices here for Walrein are quite a lot, but Molk chose Roar and Ice Beam, and I will cover why in a second. The Speed on the EV spread is interesting, because everyone knows speed creeping is a necessity. The current spread outspeeds the base 67 mark and mons that speed creep that, eg bulky Golurk. This lets it set up the SubTect cycle on mons such as Lanturn. Now, Walrein uses Roar and Ice Beam here, each for a specific reason. A lot of mons like to set up on Walrein in hopes of breaking through it, but Roar puts an end to any such plans, and racks up more entry hazard damage. The major annoyance would've been Klinklang, which could otherwise Sub and start setting up all over Walrein. Now, considering the tremendous amount of Toxic Spikes support here, Walrein can afford to skip out on Toxic itself, which makes Roar the more desirable option. For the main attacking move, Molk made the choice to use Ice Beam, mostly due to more PP and general reliability.
A couple of cores can be seen here, mainly Qwilfish + Torterra as a hazards laying core and Qwilfish + Torterra + Spiritomb as the true defensive backbone of this team. Cryogonal + Qwilfish function as the catch alls for the set-up sweepers on the special and physical side of the spectrum respectively. This all demonstrates further the solidity of the defensive cores of this team.
Now, as for weaknesses, since this is such a well built stall team, there aren't that many, but considering this is Gen V and one cannot cover everything with 6 mons, there are guaranteed to be some. First of all, the biggest threat I see to this team is Clefable. The scariest variant for this team imo is the CM variant, which can pose problems due to it being able to shrug off residual damage. A simple attacking moveset of Thunderbolt + Ice Beam allows it to massacre your main core, barring Cryogonal. Atm the best answer is Haze/Taunt/Roar, but none of this actually KOs Clefable, making me wonder how the team defeats it. Also, other threats include powerful physical mons, eg Druddigon. Choice Band Druddi can deal massive damage if it comes in on Torterra/Qwilfish, mostly because the team is so special defensively oriented, and this thus makes physical powerhouses problematic to deal with if you can't stall them out or get WoW on them.
This is quite an interesting Hail Stall team overall due to the tech Torterra usage, which does a splendid job of supporting its teammates and maintaining the stally pressure. The cores are strong and the hazards support is excellent, and Walrein is king. The goal of this team is attained effectively through the combination of all these elements, thus making this a nice Hail Stall team.