What are pokemon that make good walls?
Now this is an open ended question and a half.
Special:
Blissey
Regice
Snorlax
There are others but these are the best, Blissey is the best of the 3 hands down due to recovery move. Rest talking snorlax however i feel should be more popular than it is.
Physical:
Skarmory
Gliscor
Rhypherior
Forrestress
Donphan
Tangrowth
All these can be considered, Gliscor and skarm win because of roost though. Rhypherior and Donphan has awsome attacking power as well as defense, they can also set up Stealth Rock. Tangrowth, while not a proper wall, takes hits very well. Forrestress Is very sturdy too and along with skarm is one of the best spikers, watch out for fire attacks though.
Mixed:
Cresselia
Bronzong
Dusknoir
Uxie
Umbreon
I'm sure i've missed stuff out of this. These can specialise to be better at taking physical or special attacks or stay mixed. Cresselia is often used as more of a special wall and infact is probably as good as blissey in this respect. Bronzong has useful resists and an immunity to earthquake if levitating. Umbreon is set up fodder but usable, Taunt switch in, mean lok it, baton pass to counter, cool points for you if it works. Dusknoir has a useful rapid spin immunity if you use spikes or stealth rock a lot.
This is by no means a comprehensive list, there are many others that can be considered good for taking hits. Bulky swampert resists the common stone edge and has respectable defenses. Bulky Gyarados can counter the very scary Garchomp. Milotic is generally good and can put things to sleep and with special defense EV's can be considered a decent Specsmence counter. If its specsmence you are particulary scared of when wanting to wall special hits then consider empoleon, high sp.def, draco meteor resistance and ice beam for the win.
So what makes a good wall? High desired defense, high HP, reliable recovery not called rest (unless its of the sleep talking variety) and decent immuninties.
EDIT: Also if you need it, advice for EV's. If something has high defnse but low HP (as is the case with dusknoir as well as others) you will want to pump more into HP than the defenses. If its the other way round (as with the case of hariyama and Vaporeon) then go for defenses first.