Hello this is Cletus also known as Cletus1 (My Showdown Account) and this is the team i mostly use in SM OU. I like to build my teams with the intention of countering the entire metagame as best as i can. While i do think the team is good i'd like to see what other people think about it.
Chesnaught @ Leftovers
Ability: Bulletproof
EVs: 252 HP / 252 Def / 4 SpD
Impish Nature
-Wood Hammer/Seed Bomb
-Poison Jab
-Spikes
-Synthesis
When I started making this team the first thing I looked for was an answer to defensive and Z Stone Edge Landorus, and i came up with Chesnaught. Chesnaught checks certain Landorus, Tangrowth, Mega Swampert, Tapu Bulu, Both Tyranitars and lays up Spikes for free on Ferrothorn and Mega Venusaur.
I didn't see a need for specified EVs so i just went with max HP max Def Bold, but if you want you can run some SpD so you can also check Ice Beamless Ash Greninjas. Bulletproof is used because it gives Chesnaught free immunities to Sludge Bomb, Shadow Ball, and various other moves. Leftovers is the preferred item to gain passive recovery but a weakness berry or Rocky Helmet could be used if you want.
I had to choose only one of Chesnaught's STAB's for reasons I'll explain later but the one i choose was his grass STAB so he can deal decent damage to Landorus. I use Wood Hammer because i feel like Seed Bomb makes him too weak but if you don't want to deal with recoil than Seed Bomb is your best bet.
I use Poison Jab over Chesnaught's STAB fighting moves so he can function as a Tapu Bulu check. Spikes can provide valuable chip damage and Synthesis is for semi-reliable recovery.
Mantine @ Leftovers
Ability: Water Absorb
EVs: 252 HP / 200 SpD / 56 Spe
Calm Nature
-Scald
-Roost
-Toxic
-Haze
After Chesnaught I decided that i needed a check to the tiers fire types and I felt like Mantine was the best fit. Not only is Mantine a fantastic check most of the tiers fire types like Mega Charizard Y, Volcarona and Heatran but it is also a great answer to the tiers water types such as: Keldeo, Ash Greninja, Manaphy, Kingdra, Suicune and some others.
The EVs and nature are set for Mantine to deal with special attackers while the 56 Spe is used to outspeed Adamant Alolan Marowak and hit it with a Scald. Water Absorb is the only ability Mantine should use since an immunity to water means an immunity to scald which is always nice.
Scald is Mantines only offensive move, potentially burning a threat is always nice whether to neuter their attack or negate their Leftovers. Toxic and Haze are Mantine's ways of beating special attacking set up sweepers like Manaphy and Volcarona. Finally roost is Mantines newly acquired means of reliable recovery
Zapdos @ Rocky Helmet
Ability: Static
EVs: 240 HP / 252 Def / 16 Spe
Timid Nature
-Discharge/Thunderbolt
-Heat Wave
-Roost
-Toxic/HP Ice
Zapdos is actually the second member of Operation: Counter Z Move Landorus. Chesnaught was the first member checking Z Stone Edge while Zapdos Somewhat checks Z Fly. Zapdos also checks various other pokemon in the tier such as: Mega Pinsir, Celesteela, Ferrothorn, Skarmory, Toxapex, and Kartana.
The EVs on Zapdos are primarily meant to take physical hits while the 16 Spe plus Timid nature is used to outspeed base 70 speed pokemon such as Bisharp. Static and Rocky Helmet are used to punish U-turn and other contact moves like rapid spin, however you can use leftovers instead if you'd prefer the passive recovery.
An electric move is needed but whether it is discharge for an increased para chance or thunderbolt for increased damage is up to you. Heat Wave is also needed to deal with the various grass types in the tier such as Tapu Bulu, Kartana, and ferrothorn. Roost is obvious but be careful of when you use it since you will be weak to ground will roosting. The last move can be either toxic or HP Ice; HP ice if for ground types while Toxic is for the various other things that want to switch in.
Slowbro @ Slowbronite
Ability: Regenerator
EVs: 252 HP / 232 Def / 24 SpD IVs 0 Spe
Relaxed Nature
-Scald
-Psyshock
-Iron Defense
-Slack Off
Slowbro also known as "Mr save me from Medicham" and the third member of Operation: Counter Z Move Landorus. Mega Slowbro can eat an attack from a +2 Landorus and then proceed to Iron Defense up and recover BUT only if Landorus used his Z Move already. Mega Slowbro also checks most of the physical attacking pokemon in the tier such as Mega Charizard X, Mega Medicham, Kyurem B, Zygarde, Garchomp and many others.
Most of Slowbro's EVs go into making his defense high enough to deal with Landorus but i also put some into his SpD to make stray Earth Powers from Kyurem B do less. The reason why he is relaxed instead of Bold aswell as having 0 Spe IVs is to make him outspeed Alolan Marowak under Trick Room.
Scald is ran on Slowbro for the same reason why Mantine has it; while Psyshock is to have a way to damage Keldeo and Toxapex. Iron Defense is used to basically negate opponents Swords Dances or Dragon Dances while Slack Off allows you to win in the long run due to the ability to heal.
Excadrill @ Assault Vest
Ability: Mold Breaker
EVs: 252 HP / 4 Atk / 252 SpD
Careful Nature
-Earthquake
-Iron Head
-Rapid Spin
-Rock Slide
So far my team was showing a major weakness to electric, fairy, psychic, and dragon types; lucky Excadrill has all of that covered aswell as providing me hazard removal. Excadrill has the ability to check top tier threats such as Tapu Koko, Magearna, Tapu Lele, Latios, clefable and many more.
Excadrill needs all of his EVs to be invested into HP and SpD aswell as an Assault Vest in order to reliably check these hard hitting pokemon. Mold Breaker is the only ability that Excadrill has that functions without a sandstorm so use that one.
Due to Assault Vest working the way it does Excadrill can only use attacking moves. Earthquake and Iron Head are STAB while Rock Slide hits Landorus without making contact and Rapid Spin clears Hazards.
Clefable @ Leftovers
Ability: Unaware
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
-Moonblast
-Moonlight
-Stealth Rock
-Heal Bell
Clefable was the last pokemon I choose for this team, neatly tying it up with a Stealth Rock user that threatens out Mega Sableye, checks Mega Heracross, provides cleric support with Heal Bell, and taking care of some set up sweepers that might've bypassed my other pokemon.
Max Def and the Bold Nature with the Unaware ability are used to take care of Zygarde if it gets out of control aswell as dealing with Z Fly Salamence and Dragonite
Clefable's moveset should be self explanatory: STAB, recovery, rocks, and curing statues aliments.
Threat List:
While Slowbro can deal with Landorus after it uses it's Z Move, before hand you have to guess the right Z Move or just lose a pokemon which can let another pokemon sweep you.
All Out Pummeling Magearna could easily plow through Excadrill with some chip damage.
252 SpA Magearna All-Out Pummeling (190 BP) vs. 252 HP / 252+ SpD Assault Vest Excadrill: 260-308 (61.3 - 72.6%) -- guaranteed 2HKO
Depending on the set Protein Greninja could run through my team
Since I have no trapper or Magearna, Hoopa can just claim a kill every time it comes in.
My Electric Immunity is weak to fire which means Mega Manectric can do serious damage to my team.
Thank you for looking at my team, I am both hopeful and excited to see some feedback.