If I missed something or got something wrong, experienced battlers plz slap me nicely and tell me. Actually just tell me o3o
Ambiguous question. Overall bulk, Special Bulk or Physical bulk?
You can't define the absolute bulkiest Pokemon in each tier - each is affected by different stats, typing etc. I'll do a rough sketch of some of the most in each tier.
Gen 5 Ubers
Lugia - 106 / 130 / 154 Bulk mate. Access to Roost. Has Multiscale. Has Whirlwind. Called the Great Wall. Need I say much more?.
Giratina - 150/120/120 Bulk. Also known as the great wall. Dragon Tail and Roar. RestTalk is reliable enough :P.
Soul Dew Latias- 120 SpD is all it needs with Soul Dew to outmatch even the most specially defensive Pokemon in the whole tier. With a fast Light Screen even Choice Specs Kyogre can't hope to dent it, and Roost gives it the ability to recover fast.
Gen 5 OverUsed
Blissey/Chansey - you knew the pink blobs were coming in terms of Special Defense. Awesome Special Defense + Amazing HP = GL breaking through these pink boys with special attacks. Reliable recovery in Wish + Protect and Softboiled sweetens the deal.
Skarmory - Premium defensive Pokemon. Reliable recovery in roost, a nice Steel typing, base 140 Defense and the ability to lay hazards and phaze.
Ferrothorn - Good typing, good stats in 74/131/116 and a nice movepool makes this guy laugh at alot of Physical attackers, and also function as a great defensive pivot and mixed wall.
Specially Defensive Jirachi, Rotom-W, Specially/Physically defensive Celebi, Specially defensive Heatran, Defensive Gliscor and Defensive Forretress are just a few more, all with good typings, good movepools and the potential to laugh at alot of the tier's offensive Pokemon.
Gen 5 UnderUsed
Cresselia - 120/120/130 bulk.
Once regarded as one of the best walls in the game, Cresselia has fallen far from its throne. It is the bulkiest mixed wall in the series bar Lugia and Giratina
:D! Though it's typing is bad, making it drop, it's got a solid movepool and great defensive stats.
Registeel - 80/150/150 - a solid wall with a nice Steel Typing giving it a range of resistances and only 3 weaknesses. Best of the Regis :D!
Bronzong - 67/116/116 - Only one weakness, Fire or ground you choose depending on ability. If put on a rain team, (especially in OU) Guess what. No weaknesses. So great typing, excellent ability, and a decent movepool. More a tank than a wall, but heck one of the most bulkiest tanks.
Suicune. One of the most annoying Pokemon to run around, I remember seeing this guy take a +6 Extremespeed from Deoxys (barely) using the CroCrune set. On the topic of CroCrune, watch and laugh as your opponetns fail to do anything to you and you set up with Calm Mind and wreck with Scald.
Everyone's favourite Duck Tank, Porygon2.
When someone takes the term "bulky attacker" too far, Porygon2 is the result.
Specially Defensive Empoleon, Defensive Milotic, Eviolite Gligar, Slowbro are some more of the bulky Pokemon in the UU tier.
Gen 5 RU
Amoonguss buddy. Impressive bulk, Regenerator, Solid typing and Spore. Lez get this rolling.
Uxie - 75/130/130 bulk is nothing to laugh at in RU, and with a movepool full of nice support moves, Uxie is friggin annoying >:C
Quagsire - not the greatest defensive stats but one word - Unaware. It ignores boosts :>
Tangrowth - Another awesome grass type physical defense Pokemon. Regenerator, excellent defensive bulk and an excellent special attack makes this guy a deadly tank.
while an astonishing base 200 Defense backed by a great base 75 HP makes Steelix one, if not THE, premier physical wall in the RU tier
Eviolite Ferroseed, Slowking and Sigilyph to name a few more.
Gen 5 NU
Alomonola with Wish + Protect and a massive HP Stat makes it an excellent physical wall in the NU tier.
Eviolite Misdreavus - this thing walls basically all physical attackers in the tier, with Will-o-wisp and great bulk.
Bastiodon - Great defensive stats.
Wielding massive defensive stats, a typing that gives it a bunch of nifty resistances, and the ability to set up Stealth Rock and phaze with Roar, Bastiodon has a solid niche on defensive teams.
Lickilicky - 110/95/95 is pretty darn good bulk, and with wish+protect as a strong form of recovery
Weezing, Miltank, Tangela, Shuckle apparently to name a few more :P
Gen 5 LC
Everyone here has eviolite if you're bulky so the following Eviolite users;
Bronzor - The baby Bronzong, this thing shares the same advantage as it. A great staple for Gen 5 LC Stall teams.
Frillish - The baby Jellicent, it's unique typing and good movepool make up for some of it's lower stats compared to others. However it still has great special defense and respectable HP and Defense
Lileep stands out as traditionally one of the best walls in Little Cup.
Gud defenses, decent typing I can't be bothered to say more o3o
Koffing - Base 95 Defense is great in LC, and put that with Eviolite - bam, Koffing is here one of the best physically defensive Pokemon in LC kind of like it's older brother, Weezing.
Porygon, Shieldon, Tentacool bla bla bla are all nice bulky Pokemon in LC :3
There aren't any tiers for NU and RU, UU tier is dodgy and alot of suspect testing is going around so I'll introduce some of the newer guys this gen.
Florges the mighty flower - The new Pink Blob I mean Flower of this generation, this thing functions as a great special wall with the potential to do some decent damage too. Fairy type :DDD
Sylveon the new eeveelution - also a solid specially defensive Pokemon :3!
Carbink the new shuckle ripoff with higher HP! And lower overall defenses. It's like Deoxys-D but alot worse qq.
Furfrou! With an ability that reduces physical damage, access to Cotten Guard, this thing is annoying for physical attackers
Aegislash-Blade! Not a wall, but bulky nonetheless and designed for setting up
Avalugg - perhaps the most physically bulky Pokemon introduced this gen :3 and it has access to recover!
Stuff like Mega Aggron, Mega Heracross, Mega Gyarados etc.
These guys all get super bulky after Mega-evolving, letting them setup so they can wreck your life.