Why would you make Slowking try to tank and tank guts swellow? O_o Nothing that doesn't resist normal/flying can tank it. Slowking does just fine tanking physical attackers, and he can tank special attacks really well, obviously. Slowking tanks a ton of the tier, but he obviously has trouble with some of the threats you mentioned. However, Slowking is switching a ton, so as long as there aren't a bunch of threats that can force it out on a team, Slowking does amazing.
Lady Salamance, I've been seeing a lot of pokemon like Zebstirka, Gigalith, Butterfree, Magcargo, Ramparados, etc. (Golem is honestly quite a bit better, ground-rock is a better dual typing and golem also has sucker punch.) The NU ladder is better then it was yesterday, though.