I choose Chansey
as my preferred Special Wall. It gets Eviolite which helps it takes hits far better. Unlike Blissey it isnt brought down by any Physical move thanks to Eviolite boosting its Defense also. Lack of Leftovers may seem bad at first but Soft Boiled helps. Chansey may have less Special Attack but the only attack commonly used on Chansey is Seismic Toss so yeah Chansey gets my vote.
gets my vote as a physical wall of my choice. It is extremely bulky and can take physical hits like a champ. Not only that but Groudon can also dish out some damage if needed. It also brings in the Sun and can do a fair bit of PHazing with Dragon and can set up Stealth Rocks. So I would pick Groudon as my all purpose Physical Wall.
EDIT:I added some sprites just for the effect. Man Groudon looks badass !