Swampert

Swampert is an excellent wall. Its great defensive typing gives it resistances and immunities to Fire-, Poison-, and Electric-type attacks from the likes of Infernape, Alolan Muk, and Iron Thorns, and it threatens them with Earthquake. While there is some competition for the Water-type slot on teams, Swampert is unique in its ability to simultaneously threaten Electric-types and pivot out with Flip Turn, often slowly enough to bring its teammate in completely safely. On top of this, Swampert also has access to Knock Off, which is valuable utility to cripple item-reliant Pokemon like Talonflame, Avalugg, and Registeel, and Roar, which allows Swampert to challenge setup sweepers like Cresselia and Oricorio-E. However, its limited recovery options make Swampert vulnerable to being worn down over the course of a battle, meaning it won't be able to check these aforementioned setup sweepers long-term. Swampert's 4x weakness to Grass-type attacks also hampers it, as it struggles against common Grass-types like Tsareena, Breloom, and Brambleghast. On top of this, many Pokemon like Chandelure, Gallade, and Iron Thorns carry some way to surprise Swampert with Grass-type coverage, whether that be Energy Ball, Leaf Blade, or Tera Blast Grass.