Ok here are some:
Onix: Physical Wall
Evs: 252 Def/252 Hp/4Atk
Onix is a underrated Pokemon. But, it has massive defense with a base of 160. With the eviolite, it is boosted up to (correct me if I'm wrong) 240. It can basically wall any phyiscal attackers.
Stunfisk: Special Wall
EVs: 252HP/252Sp.def/4sp.atk or 4 def
Oh sure everyone hates Stunfisk. But when its stalling you like a boss, ure hate it more ;)
Underrated, but its 99 base sp. def and 108 base hp can make a sp. wall. With Scald to burn and stop physical attackers, it is a wall.
Hope I helped!