Shuckle

Balanced Setup Wall
Name: Shuckle

Item: Leftovers
Ability: Sturdy
- Encore
- Stealth Rock

- Rest

- Toxic
EVs: 252 HP / 228 SDef / 28 Def

Nature: Bold (+Def, -Atk) 

Moves:

Encore is used to switch to appropriate counter or mess up Subs and Statboosts. It an also force switch from opponent.

With Stealth Rock you can set up, and take benefit from Encored switches and saving it from another team pokemon.

Rest is pretty self-explanatory, your only means to survive and wall.

Toxic to outstall other pokemons. 

EVs & Nature:
With these values you can get max 553 Def & SDef.
This works the same way with Bold/Impish/Calm/Careful, if you get good IVs with another nature just change EV train accordingly. Primary IV focus on HP, Def and SDef.

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Stall Boost
Name: Shuckle

Item: Leftovers / Chesto Berry
Ability: Sturdy

- Acupressure
- Rock Slide

- Rest

- Toxic
EVs: 252 HP / 252 Def / 4 SDef

Nature: Impish (+Def, -SAtk)

Item:

Chesto Berry can also work pretty well in this build, although it's worse on the long run, it helps on the early stages before Acupressure helps you to survive. 

Moves:

Basically Toxic non-immunes, and spam Acupressure, beware of PHazers though, this is best used mid/late game. It's preferable if you have some passive damage working as it will add up when your opponent starts switching.

Rock Slide is there to make use of Acupressure Attack boosts and kill Toxic immunes.
Rest to recover HP and keep working. 

EVs & Nature:

Since this build usually can hold versus super-effective water stallers, I opted to swift EVs for Def (giving max 614 Def and 497 SDef) to hold versus Toxic immunes and their common physical super-effective STAB attacks (Rock, Steel).