Regice

[WouW]

#378 Regice
Ice
Clear Body: Stats can't be lowered by the opponent
80HP/50Atk/100Def/100SpA/200SpD/50Spe

Sleep Talk

Regice @ Leftovers
Clear Body/Calm
252HP/252Def/4SpD
Rest
Sleep Talk
Ice Beam
Seismic Toss/Thunderbolt

With insane special walling capabilities, Regice is very sturdy but it lacks a good recovery move so it's a good candidate to Rest/Sleep Talk.
Ice Beam for STAB, obviously, and Thunderbolt for the Bolt/Beam combo or Seismic Toss for overly Calm-Minded Pokés such as Suicune.

Attacking wall

Regice @ Leftovers
Clear Body/Calm
252HP/252Def/4SpD
Ice Beam
Thunderbolt
Thunder Wave
Psych Up/Focus Punch

Still able to wall, although this time without any form of healing, so Wish support might be useful. Bolt/Beam is here again. Thunder Wave to cripple fast sweepers, and Psych Up for Calm Minders and Focus Punch vs. Weavile or Tyranitar.

Scarf

Regice @ Choice Scarf
Clear Body/Timid
252SpA/252Spe/4HP
Ice Beam
Thunderbolt
Hidden Power Rock
Explosion

Regice outspeeding things like Neutral natured Gengar, Garchomp, Zapdos, Flygon, Salamence and +speed natured Houndoom, Jynx, Yanmega, Leafeon and Gliscor and having moves to deal with those could catch people by surprise. Could be used as revenge killer. If Regice gets low on health, switch it in and explode.

Other options

You could make a set around Curse and Counter - after a Curse, you can survive a lot of dangerous stuff and Counter it for a quick KO. If you're afraid of steel bugs, use HP Fire. Rock Polish could be used for sweeping.

EVs

With a base 200 Special Defense you don't usually need EVs in that, but with a +nature you can survive some dangerous sutff like Salamence's Specs Flamethrower. Max HP and Defense allows getting in easier from things like Earthquake.

Troublesome Pokémon

Tyranitar, Heracross and Metagross all have Super Effective physical STAB attacks and those hurt. Most Fighting-types are bad also.

Written by WouW