Team building Process:
Sandaconda @ Rocky Helmet
Ability: Shed Skin
EVs: 252 HP / 168 Def / 88 Spe
Impish Nature
- Stealth Rock
- Earthquake
- Glare
- Rest
My initial intention is to build a team around Sandaconda, thanks to its immense physical bulk it helps to control a large part of the physical attackers, Rest and its Shed Skin ability is a viable recovery method. It also provides speed control with glare.
Even if Sandaconda can take special hits, he still needs to fight Slowbro, Slowking, Kyurem, Tapu Fini, and so on. So you need a special wall like Blissey.
Blissey @ Heavy-Duty Boots
Ability: Natural Cure
EVs: 200 HP / 252 Def / 56 SpD
Bold Nature
- Seismic Toss
- Soft-Boiled
- Toxic
- Teleport
Even though he is less bulky than the Eviolite-wearing Chansey, the ability to have Heavy-Duty Boots gives Blissey a huge advantage over Chansey by ignoring all entry hazards and makes him an exceptional pivot. Teleport also plays an important role in boosting Blissey's pivot capabilities, allowing her to build momentum for her teammates quite easily by taking hits with her great special bulk and getting in safely. Blissey makes it easy to block special attackers that are Volcarona, Hydreigon, Dragapult, and so on.
Clefable @ Leftovers
Ability: Magic Guard
EVs: 252 HP / 200 Def / 56 SpD
Calm Nature
- Wish
- Protect
- Moonblast
- Knock Off
Clefable is a fantastic defensive pokémon, his immunity to avoiding residual damage from Magic Guard and his wide variety of useful moves make him one of the best. It can switch against offensive threats such as Dragapult, Garchomp and Zeraora, while it is also good at absorbing status and Knock Off hurts the majority of the tier, this has a good companion that gives it good versatility, that is Hydreigon with Defog.
Hydreigon @ Leftovers
Ability: Levitate
EVs: 252 HP / 168 SpD / 88 Spe
Calm Nature
IVs: 0 Atk
- Dark Pulse
- Earth Power
- Roost
- Defog
Hydreigon has very good synergy with Clefable and Toxapex, so it has a coverage that is Earth Power to put a stop to Heatran.
Toxapex @ Shed Shell
Ability: Regenerator
Shiny: Yes
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
IVs: 0 Atk
- Recover
- Scald
- Haze
- Toxic Spikes
Toxapex with Scald allows you to strongly damage pokémon like Landorus-T, potentially burning enemies like Garchomp and Ferrothor, while Haze against the use of stat increase moves, finally Toxic Spikes is an option to wear down pokémon on the ground like Garchomp, Rillaboom and Tapu Fini, more defensive pokémon like Tyranitar and Tangrowth. The Shell Shed item is used to deal with Heatran.
Ferrothorn @ Leftovers
Ability: Iron Barbs
EVs: 252 HP / 80 Def / 176 SpD
Careful Nature
- Iron Defense
- Body Press
- Knock Off
- Leech Seed
Ferrothorn stands out as a great defensive pokémon, being able to take hits well from Zeraora and Excadrill, as well as take advantage of passive pokémon like Clefable and Toxapex, especially defensive ones, to configure entry dangers. In particular, Ferrothorn with Body Press defeats Pokémon like Bisharp while pressing Hydreigon and Hazard Eliminators like Corviknight, Mandibuzz, and Excadrill. Knock Off seriously limits the usefulness of some pokémon in the course of a game, Heavy-Duty Boots users like Mandibuzz and Rotom-H, as well as Leftovers users
as Corviknight 
can easily beat it, but when you are facing Magnezone 
alongside with Rillaboom, it’s a whole different story. Even duos with two Pokemon that you can check with the same answer can be problematic if the first one leaves this answer in range of the second one. There are way too many cores and sets and you will struggle against some of them even with a very good stall team, and that’s why stall is not that much popular as you rely a lot on having a good matchup. Now, if some matchups are free and others are near impossible, most of the time, you will have to play well to win more even matchups and something extremely important is to identify at the beginning of the game what are the threats in the opposing team, what are their ways of winning and how can you deal with each of these threats. This thought process is important in order to avoid letting die a Pokemon that prevent a sweep or letting the opponent overwhelm your Pokemon one after the other. Anyway, this was a more general introduction about playing stall as you seem to be interested in this playstyle. Let’s move to the actual rate of the team.
, Clefable 
and Blissey 
are Pokemon used in almost any stall team because of all the utility they can bring to this kind of teams. Blissey is an incredible special wall with a lot of utility moves like Heal Bell and Stealth Rock. Clefable is most of the time the anti-setup Pokemon thanks to its ability Unaware and can act as a great win condition (because yeah you can have win condition in stall and don’t necessarily need to have 6 passive Pokemon) with Calm Mind + Unaware denying the opposing setup attempts. Toxapex brings a lot of useful resistances alongside with a colossal bulk and very useful moves like Haze, Knock Off, Scald, Toxic Spikes… Regenerator is also a great ability to scout some Choice users without being forced to leave a Pokemon low in health in case of a wrong prediction. This trio is thus a great basis for your team and these Pokemon should definitely be kept. Hydreigon 
is an interesting choice. At first glance, this Pokemon seems to be an offensive beast. However, it has a good bulk with a very nice typing and brings a strong answer to Heatran 
, one of the most threatening stallbreaker. Being able to handle Heatran is very important for stall teams as it is one of the most common Pokemon in the tier and its trapping set will easily force kills otherwise. Sandaconda 
seems to be the star of the team and it brings an Electric immunity which is important in this kind of team if you want to prevent VoltTurn spam and to deal with threatening Electric types like Zeraora 
for instance. If it was up to me I would say that Hippowdon 
can do the same job better and this is the reason why Hippowdon is a way more common choice. However, Sandaconda has some nice moves like Glare and Coil and a way more interesting ability so it might have a niche here. (I had a little debate about why it’s hard to use lower tiers Pokemon in OU and more globally about creativity in building here if you want to check: 
is probably the Pokemon to change here. This may seem counterintuitive but even if Ferrothorn is indeed a great defensive Pokemon, it doesn’t fit well in stall teams. Being unable to properly recover its health means that it will be quickly weakened and overwhelmed against offensive teams with strong breakers. This is something you want to avoid as in a very passive team you will need to be able to come in on the same threats a lot of time. Moreover, even if Ferrothorn is in theory a good Grass resistance, it can’t deal with the most threatening Grass types like Rillaboom 
and Tapu Bulu 
who are extremely hard to handle with your current team.
check, a check to most Swords Dance user with its Iron Defense set and a way to deal with most Tapu Lele 
with some SpD investment (you still need to make the good predictions as Focus Blast has a high chance of 2HKO). Skarmory 
could also fit in that slot, but Corviknight is more useful here for checking Tapu Lele and providing Pressure (which is useful to beat Stealth Rock setters as they have less PP than Defog thanks to Pressure). I would thus use an Iron Defense Body Press set with the SpD needed to take Tapu Lele’s Psychic after Rocks. The set is just here:
, Garchomp 
, Weavile 
, other Clefable 
or other Clefable 
or Blacephalon 
. Here is the set:
with Whirlpool. Rocky Helmet may be a bit more useful because I feel that having a Rocky Helmet user is always nice in stall to punish some physical attackers and U-turn user that may be hard to chip otherwise. Scald is also an option over Toxic Spikes, but Toxic Spikes is a fine choice.
/ Slowbro 
switching out. Nasty Plot is another option that will allow Hydreigon to pressure the opposing team if needed and may help a lot if you happen to face another passive/defensive team.