Cloyster

There is more to this shady clam than what meets the eye. Cloyster's stat spread might scream "physical wall," but that's hardly the case, for it gets access to arguably the best boosting move in the game: Shell Smash. After just a turn of setup, Cloyster turns into a wrecking ball that can mow through entire teams with ease. With Skill Link, Cloyster possesses a powerful STAB Icicle Spear, which has an enormous 187 BP after STAB, as well as a great coverage move in Rock Blast; this ensures that even Substitute users cannot stop Cloyster's rampage. A massive base 180 Defense makes Cloyster all the more difficult to revenge kill, as it can comfortably survive powerful priority moves such as Mach Punch from the likes of Breloom and Conkeldurr even after a Shell Smash. Unfortunately, Cloyster's horrendous Special Defense means it simply can't take a special attack to save its life, and a weakness to Stealth Rock makes switching in even more difficult. It also finds it difficult to get past bulky Water-types such as Jellicent, which can take Cloyster's boosted attacks with ease and burn it, rendering it useless. Underestimating Cloyster on the basis of these shortcomings will be suicidal, though; it can run through your team like a hot knife through butter.