The main special wall, as all we know, is Blissey, but it's over over over used. I was looking for other wall, and I found that in the D/P analysis:
Snorlax
move 1: Body Slam
move 2: Earthquake / Crunch / Pursuit / Fire Blast
move 3: Sleep Talk
move 4: Rest
item: Leftovers
nature: Careful
evs: 220HP / 36DEF / 252SPDEF
It have problems with Steel types if it carries Crunch, with Ghost if Fire Blast and with Flying if Earthquake. But it can stand very well lots of Special Sweepers.
Regice
move 1: Ice Beam
move 2: Rest
move 3: Sleep Talk
move 4: Thunderbolt / Toxic / Seismic Toss
item: Leftovers
nature: Calm
evs: 252HP / 252DEF / 6SPD
An Sleeptalker, the same as Snorlax, but it have better offensive capabilities, and with a 100 defense stat and 200 special defense stat it can stand a lot of hits, but it have problems with his weakness, and with Raikou if you choose Thunderbolt in the fourth slot.
Ludicolo
move 1: Rain Dance
move 2: Surf/Energy Ball/Grass Knot/Giga Drain
move 3: Ice beam
move 4: Leech Seed
item: Leftovers/Wet Rock
ability: Swift Swim
nature: Calm
EVs: 204HP / 76SPATK / 124SPDEF / 104SPD
It has good Special defense stat, and it can stand some strong hits, furthermore, if it's raining, it can OHKO Salamence, before it kills you with his Draco Meteor. The main trouble, is Heracross.
I also thought about Mantine, but his 4x electric weakness is a big trouble.
We should be more original.
PD: Sorry for my horrible english xD
Edit: A big bug in the comments of Snorlax.
Snorlax
move 1: Body Slam
move 2: Earthquake / Crunch / Pursuit / Fire Blast
move 3: Sleep Talk
move 4: Rest
item: Leftovers
nature: Careful
evs: 220HP / 36DEF / 252SPDEF
It have problems with Steel types if it carries Crunch, with Ghost if Fire Blast and with Flying if Earthquake. But it can stand very well lots of Special Sweepers.
Regice
move 1: Ice Beam
move 2: Rest
move 3: Sleep Talk
move 4: Thunderbolt / Toxic / Seismic Toss
item: Leftovers
nature: Calm
evs: 252HP / 252DEF / 6SPD
An Sleeptalker, the same as Snorlax, but it have better offensive capabilities, and with a 100 defense stat and 200 special defense stat it can stand a lot of hits, but it have problems with his weakness, and with Raikou if you choose Thunderbolt in the fourth slot.
Ludicolo
move 1: Rain Dance
move 2: Surf/Energy Ball/Grass Knot/Giga Drain
move 3: Ice beam
move 4: Leech Seed
item: Leftovers/Wet Rock
ability: Swift Swim
nature: Calm
EVs: 204HP / 76SPATK / 124SPDEF / 104SPD
It has good Special defense stat, and it can stand some strong hits, furthermore, if it's raining, it can OHKO Salamence, before it kills you with his Draco Meteor. The main trouble, is Heracross.
I also thought about Mantine, but his 4x electric weakness is a big trouble.
We should be more original.
PD: Sorry for my horrible english xD
Edit: A big bug in the comments of Snorlax.