I have 2 tried and tested physical walls I use if I'm not inclined to use Skarmory.
Slowbro@Leftovers
Bold, 252 defense, 216 hp, 40 special attack
Calm Mind
Surf
Grass Knot
Slack Off
Great because if it gets off a few minds it can wall special attacks as well and becomes an offensive powerhouse with the potential to straight sweep, and because it will beat Skarmbliss any day of the weak. It may have a few liabilities with typing, but with its considerable bulk and Slackoff Slowbro can shrug off super effective attacks like a beast. If Garchomp is an issue, nuke grass knot in favor of hp ice, though Surf should be sufficient and other waters (notably Vaporeon and Milotic) will walk all over you.
Vaporeon@Leftovers
Bold
252 defense, 220 hp, 36 special attack
Surf
Toxic
Wish
Protect
Ever seen a Vappy in heat? It's vicious. High special attack and decent power move, Toxic, and protect is a potent combo, and with wish coupled with leftovers you'll be getting back insane amounts of health every turn while your opponent dwindles. Just watch out for the sleep clause.
Bold Venusaur can make itself useful as well, with sleep powder and leech seed/growth.