Jolteon
Jolteon is a lot better this generation primarily because of terastalization granting it the ability to touch Grass-, Ground- and Dragon-types like Shaymin, Rotom-C, Gligar, and Goodra with Tera Blast [Ice] while Tera [Fairy] is a middle ground to hit the aforementioned types neutrally and super effectively, respectively, while being a great defensive typing to immune to notably be immune to Draco Meteor from Goodra and provide more survivability against things like Close Combat from Choice Scarf Passimian and Sucker Punch from Tera [Dark] Toxicroak. Alternatively, Jolteon can run Substitute to take advantage of a number of scenarios such as: clicking Substitute + Terastalizing into [Fairy] to take advantage of a Draco Meteor, Volt Switch Rotom-C vs Volt Absorb, and to avoid Sucker Punch from the likes of Cacturne and Toxicroak.
Jolteon is the second fastest Pokemon in the tier right behind the Electrode-twins which notably outspeeds other swift Pokemon like Salazzle, Sneasel, and Froslass. Piloswine seems like your best defensive counter the tier has to offer due to its Ground-typing which nullifies momentum and minimizes setup opportunities. Outside of Piloswine, the metagame is filled with "checks" like Goodra, AV Hariyama, Hoopa, and Copperajah. These are only checks because they force Jolteon to click Volt Switch which means it's less likely for them to be returning damage to Jolteon, at least early game. Some physical scarfer like Bruxish / Toxicroak seems like your best route in revenge-killing such a Pokémon.
I was thinking hard about how terastalization plays into effect in Jolteon's presence in the tier. It feels more inclined/forced to terastalize to really get value to even touch Grass-, Ground-, and Dragon-types, but is this really a negative attribute? I also asked myself what is Jolteon really doing in the tier and does being the Pokemon more inclined to terastalize acts as a restriction and justification for Jolteon to not take action.
The tiering policy outlines and I quote "III.) Broken. These aren't necessarily completely uncompetitive because they don't take the determining factor out of the player's hands; both can use these elements and both probably have a fair chance to win. They are broken because they almost dictate/require usage, and a standard team without one of them facing a standard team with one of them would be at a drastic disadvantage. & IV. Unhealthy. These are elements that may not limit either team building or battling skill enough individually but combine to cause an effect that is undesirable for the metagame." Jolteon raises red flags that collide with the tiering philosophy because its presence is partially broken and unhealthy and I believe the best route for this Pokémon would be a suspect test.
Jolteon is not dropping Draco Meteors left and right but what makes this Pokémon stick out is its amazing Speed and Special Attack, Tera [Ice] / [Fairy] nuking its intended checks in Pokemon like Shaymin, Sandaconda, and Goodra, and its Escapsim route in Volt Switch allowing this Pokémon to chip down whatever Pokemon (besides Piloswine) you have intended to check Jolteon to not remotely do anything to Jolteon. Hell, even Tera [Water] Jolteon has been brought up a couple of times but I feel like that set is just inferior to just running Ice and Fairy because you're completely walled by Goodra and etc. Jolteon appreciates Heavy-Duty Boots as well as this obviously provides more longevity. Furthermore, Jolteon loves entry hazards (on a teammate) to wear down the aforementioned intended checks due to the tier having hazard control options that either: don't check Jolteon, can't comfortably switch in, and/or are setup fodder. Here is what the tier's hazard control options are looking like for reference:
. If you aren't running Piloswine, you put yourself at a disadvantage when you're actually against a Jolteon and this is a restricting aspect to have in the teambuilder and gameplay.
Goodra
Goodra is a versatile bulky special attacker that has god-like coverage such as Fire Blast, Sludge Bomb, Knock Off, and Body Press. The slug can pull off a multitude of sets such as Choice Specs, Assault Vest, and Acid Armor. Even Life Dew + Tera [Steel] has an interesting place on certain builds. Out of all of the sets, Assault Vest 
is the best set out of the three. Assault Vest provides more survivability in scenarios such as: Choice Specs Draco Meteor from Goodra & literally doing the same damage (78.1-92.7) in return & making Jolteon's Tera [Ice/Fairy] become a 3HKO (29.6-35.5) instead of a potential 2HKO. On top of that, it's a perfect balance of versatility which allows it to switch between moves like Knock Off for Heatproof Bronzong & Sludge Bomb for Grimmsnarl compared to Choice Specs. The metagame favors Heatproof Bronzong a lot more so having the utility to remove Bronzong's main recovery route in Leftovers w/ Knock Off is a lot better than relying on Choice Specs.
Goodra should be quickbanned due to its flexibility in terastalization, amazing movepool, bulk, and set up opportunities in Acid Armor. Goodra can run Tera [Fairy] which checks Dragon and Fighting-types like opposing Goodras, Heracross, and Tauros-Paldea-Blaze, and [Poison] which checks Fairy- and Poison-types like Tera [Fairy] Shaymin. It's amazing movepool is way too good for the tier and the main check that comes to mind for Goodra is Piloswine. Dachbun is an option with Tera [Steel] but I find that very restricting, similar to Piloswine vs Jolteon. If you aren't running a Dachbun with Tera [Steel], there really isn't a check for non-BP sets. What separates Goodra from Jolteon is it can run anything and everything and the suprise factor is too much for the tier to handle. Even then, Goodra can opt to run Acid Armor to take advantage of its intended checks in Piloswine, Heracross, and Sneasel.
Shaymin
Shaymin doesn't stick out right now in terms of a suspect or quick ban. Similar to Goodra, Choice Specs sets feel like a slight restriction compared to Heavy-Duty Boots (or just anything over Choice Specs) due to Seed Flare already inflicting a -2 SpD Drop. It's the perfect balance of utility with Leech Seed / Healing Wish and offense with Seed Flare + Dazzling Gleam / Earth Power which allows it to break past Pokémon like Hariyama and Copperajah. There are a couple of things that keep this Pokemon in check such as Goodra, Scyther, Levitate ID Bronzong (would be more justifiable if Goodra gets banned), and Altaria. Play Rough Shaymin feels like a neat tech on a Goodra Switch. Healing Wish Shaymin may raise a red flag only because it complements Goodra / Jolteon / Salazzle in giving them a second chance to spread misery. It's kind of like Revival Blessing + Annihilape / Broken. There are many aspects that can benefit/synergize a playstyle but arguments should be focused on the Pokémon itself and Shaymin doesn't primarily exhibits anything that breaks the tiering policy. Goodra & Jolteon sticks out on their own w/ or w/o the support of Shaymin.
Sand
Sand has made a name for itself with the additions of Lycanroc and Sandslash from the October tiering drops. What makes the hippo different than our iconic Sand Spitter (Sandaconda) is naturally having the ability to provide sand by existing which makes it a consistent option compared to waiting for a Pokémon to attack you to activate such a playstyle. Sandslash's Ground-typing and high defense stat allows it to eat attacks and act as a former wallbreaker for this archetype, allowing Lycanroc and Houndstone to have more fun. Furthermore, Houndstone loves the departure of both Snorlax and Brute Bonnet from our recent tiering slate as this gives it more wiggle room to use its Ghost-STAB. I know at first you may be contemplating if Houndstone is viable with Last Respect being banned by OU, however, its access to a powerful Poltergeist makes it a justifiable option in the metagame. Thanks to sand, Houndstone is faster than many of the standard fast-speed control options such as Bruxish and Rotom-C. Rabia has a great team featuring Bruxish and Rotom-C that acts as great momentum options that complement this offensive playstyle due to their access in Flip Turn and Volt Switch, respectively. Healing Wish options in Pokemon like Mesprit and Shaymin allow you to pretty much revive a very low sand abuser and Catalisador features this in their team. freezai made a really great video on his SCL game against Axtrix in Week 2 of SCL featuring Flip Turn Qwilfish + Eject Button Shaymin (2 pivoting options to bring the abusers in again). Overall, sand builds should be opting to run some sort of momentum option
to fully take advantage of such a playstyle in the metagame. Before the last slate, I made a team featuring 
Eject Button Brute Bonnet + 
Eject Pack Heracross. The reasoning behind this was to pretty much pressure the opponent with sleep from Spore, and if you find a position to use Spore, you grant a comfortable setup opportunity for the aforementioned Sand Rushers. Now that Brute Bonnet is banned, I wanted to maybe toy with Victreebel but nonetheless, I suggest running one of the aforementioned pivoting options!
Jolteon @ Heavy-Duty Boots
Ability: Volt Absorb
Tera Type: Ice / Fairy
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Calm Mind
- Thunderbolt
- Tera Blast
- Volt Switch / Substitute
Ability: Volt Absorb
Tera Type: Ice / Fairy
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Calm Mind
- Thunderbolt
- Tera Blast
- Volt Switch / Substitute
Jolteon is the second fastest Pokemon in the tier right behind the Electrode-twins which notably outspeeds other swift Pokemon like Salazzle, Sneasel, and Froslass. Piloswine seems like your best defensive counter the tier has to offer due to its Ground-typing which nullifies momentum and minimizes setup opportunities. Outside of Piloswine, the metagame is filled with "checks" like Goodra, AV Hariyama, Hoopa, and Copperajah. These are only checks because they force Jolteon to click Volt Switch which means it's less likely for them to be returning damage to Jolteon, at least early game. Some physical scarfer like Bruxish / Toxicroak seems like your best route in revenge-killing such a Pokémon.
I was thinking hard about how terastalization plays into effect in Jolteon's presence in the tier. It feels more inclined/forced to terastalize to really get value to even touch Grass-, Ground-, and Dragon-types, but is this really a negative attribute? I also asked myself what is Jolteon really doing in the tier and does being the Pokemon more inclined to terastalize acts as a restriction and justification for Jolteon to not take action.
The tiering policy outlines and I quote "III.) Broken. These aren't necessarily completely uncompetitive because they don't take the determining factor out of the player's hands; both can use these elements and both probably have a fair chance to win. They are broken because they almost dictate/require usage, and a standard team without one of them facing a standard team with one of them would be at a drastic disadvantage. & IV. Unhealthy. These are elements that may not limit either team building or battling skill enough individually but combine to cause an effect that is undesirable for the metagame." Jolteon raises red flags that collide with the tiering philosophy because its presence is partially broken and unhealthy and I believe the best route for this Pokémon would be a suspect test.
Jolteon is not dropping Draco Meteors left and right but what makes this Pokémon stick out is its amazing Speed and Special Attack, Tera [Ice] / [Fairy] nuking its intended checks in Pokemon like Shaymin, Sandaconda, and Goodra, and its Escapsim route in Volt Switch allowing this Pokémon to chip down whatever Pokemon (besides Piloswine) you have intended to check Jolteon to not remotely do anything to Jolteon. Hell, even Tera [Water] Jolteon has been brought up a couple of times but I feel like that set is just inferior to just running Ice and Fairy because you're completely walled by Goodra and etc. Jolteon appreciates Heavy-Duty Boots as well as this obviously provides more longevity. Furthermore, Jolteon loves entry hazards (on a teammate) to wear down the aforementioned intended checks due to the tier having hazard control options that either: don't check Jolteon, can't comfortably switch in, and/or are setup fodder. Here is what the tier's hazard control options are looking like for reference:
. If you aren't running Piloswine, you put yourself at a disadvantage when you're actually against a Jolteon and this is a restricting aspect to have in the teambuilder and gameplay.Goodra
Goodra @ Choice Specs
Ability: Sap Sipper
Tera Type: Poison
EVs: 40 HP / 252 SpA / 16 SpD / 200 Spe
Timid Nature
IVs: 0 Atk
- Draco Meteor
- Flamethrower
- Sludge Bomb
- Dragon Pulse
Ability: Sap Sipper
Tera Type: Poison
EVs: 40 HP / 252 SpA / 16 SpD / 200 Spe
Timid Nature
IVs: 0 Atk
- Draco Meteor
- Flamethrower
- Sludge Bomb
- Dragon Pulse
Goodra @ Assault Vest
Ability: Sap Sipper
Tera Type: Steel
EVs: 200 HP / 252 SpA / 56 Spe
Modest Nature
- Draco Meteor
- Knock Off
- Fire Blast
- Sludge Bomb
Ability: Sap Sipper
Tera Type: Steel
EVs: 200 HP / 252 SpA / 56 Spe
Modest Nature
- Draco Meteor
- Knock Off
- Fire Blast
- Sludge Bomb
Goodra @ Leftovers
Ability: Sap Sipper
Tera Type: Ghost / FIghting / Steel
EVs: 252 HP / 20 Def / 56 SpD / 180 Spe
Calm Nature
IVs: 0 Atk
- Protect
- Acid Armor
- Body Press
- Dragon Pulse / Sludge Bomb / Flamethrower
Ability: Sap Sipper
Tera Type: Ghost / FIghting / Steel
EVs: 252 HP / 20 Def / 56 SpD / 180 Spe
Calm Nature
IVs: 0 Atk
- Protect
- Acid Armor
- Body Press
- Dragon Pulse / Sludge Bomb / Flamethrower
is the best set out of the three. Assault Vest provides more survivability in scenarios such as: Choice Specs Draco Meteor from Goodra & literally doing the same damage (78.1-92.7) in return & making Jolteon's Tera [Ice/Fairy] become a 3HKO (29.6-35.5) instead of a potential 2HKO. On top of that, it's a perfect balance of versatility which allows it to switch between moves like Knock Off for Heatproof Bronzong & Sludge Bomb for Grimmsnarl compared to Choice Specs. The metagame favors Heatproof Bronzong a lot more so having the utility to remove Bronzong's main recovery route in Leftovers w/ Knock Off is a lot better than relying on Choice Specs.Goodra should be quickbanned due to its flexibility in terastalization, amazing movepool, bulk, and set up opportunities in Acid Armor. Goodra can run Tera [Fairy] which checks Dragon and Fighting-types like opposing Goodras, Heracross, and Tauros-Paldea-Blaze, and [Poison] which checks Fairy- and Poison-types like Tera [Fairy] Shaymin. It's amazing movepool is way too good for the tier and the main check that comes to mind for Goodra is Piloswine. Dachbun is an option with Tera [Steel] but I find that very restricting, similar to Piloswine vs Jolteon. If you aren't running a Dachbun with Tera [Steel], there really isn't a check for non-BP sets. What separates Goodra from Jolteon is it can run anything and everything and the suprise factor is too much for the tier to handle. Even then, Goodra can opt to run Acid Armor to take advantage of its intended checks in Piloswine, Heracross, and Sneasel.
Shaymin
Shaymin @ Choice Specs
Ability: Natural Cure
Tera Type: Fairy
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Seed Flare
- Earth Power
- Dazzling Gleam
- Healing Wish
Ability: Natural Cure
Tera Type: Fairy
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Seed Flare
- Earth Power
- Dazzling Gleam
- Healing Wish
Shaymin doesn't stick out right now in terms of a suspect or quick ban. Similar to Goodra, Choice Specs sets feel like a slight restriction compared to Heavy-Duty Boots (or just anything over Choice Specs) due to Seed Flare already inflicting a -2 SpD Drop. It's the perfect balance of utility with Leech Seed / Healing Wish and offense with Seed Flare + Dazzling Gleam / Earth Power which allows it to break past Pokémon like Hariyama and Copperajah. There are a couple of things that keep this Pokemon in check such as Goodra, Scyther, Levitate ID Bronzong (would be more justifiable if Goodra gets banned), and Altaria. Play Rough Shaymin feels like a neat tech on a Goodra Switch. Healing Wish Shaymin may raise a red flag only because it complements Goodra / Jolteon / Salazzle in giving them a second chance to spread misery. It's kind of like Revival Blessing + Annihilape / Broken. There are many aspects that can benefit/synergize a playstyle but arguments should be focused on the Pokémon itself and Shaymin doesn't primarily exhibits anything that breaks the tiering policy. Goodra & Jolteon sticks out on their own w/ or w/o the support of Shaymin.
Sand
Sand has made a name for itself with the additions of Lycanroc and Sandslash from the October tiering drops. What makes the hippo different than our iconic Sand Spitter (Sandaconda) is naturally having the ability to provide sand by existing which makes it a consistent option compared to waiting for a Pokémon to attack you to activate such a playstyle. Sandslash's Ground-typing and high defense stat allows it to eat attacks and act as a former wallbreaker for this archetype, allowing Lycanroc and Houndstone to have more fun. Furthermore, Houndstone loves the departure of both Snorlax and Brute Bonnet from our recent tiering slate as this gives it more wiggle room to use its Ghost-STAB. I know at first you may be contemplating if Houndstone is viable with Last Respect being banned by OU, however, its access to a powerful Poltergeist makes it a justifiable option in the metagame. Thanks to sand, Houndstone is faster than many of the standard fast-speed control options such as Bruxish and Rotom-C. Rabia has a great team featuring Bruxish and Rotom-C that acts as great momentum options that complement this offensive playstyle due to their access in Flip Turn and Volt Switch, respectively. Healing Wish options in Pokemon like Mesprit and Shaymin allow you to pretty much revive a very low sand abuser and Catalisador features this in their team. freezai made a really great video on his SCL game against Axtrix in Week 2 of SCL featuring Flip Turn Qwilfish + Eject Button Shaymin (2 pivoting options to bring the abusers in again). Overall, sand builds should be opting to run some sort of momentum option
to fully take advantage of such a playstyle in the metagame. Before the last slate, I made a team featuring Eject Button Brute Bonnet + Eject Pack Heracross. The reasoning behind this was to pretty much pressure the opponent with sleep from Spore, and if you find a position to use Spore, you grant a comfortable setup opportunity for the aforementioned Sand Rushers. Now that Brute Bonnet is banned, I wanted to maybe toy with Victreebel but nonetheless, I suggest running one of the aforementioned pivoting options!