Does anyone think that Cradily should get a ranking? With a Specially Defensive set and Storm Drain, it completely walls Tapu Fini, Milotic, Pelipper, Mega Swampert, Ludicolo, Zapdos, Tapu Koko, Mega Manectric, Suicune, Rotom Wash, Amoonguss, Gastrodon, Politoed and Kingdra, and then proceed to spam Giga Drain / Earth Power / Toxic until it wins. And if you throw in Mirror Coat it can actually surprise KO a lot more things.
I haven't had extensive experience with it, but on paper it does look promising, especially against Rain.
As a completely random niche use, it can tank a hit from Mega Gengar and surprise it with Gastro Acid to negate Shadow Tag and free up switches. In addition, with Leftovers or a pinch berry, Gengar can't even 3HKO Cradily before it dies to Earth Powers. And as we know, Gengar cores come with Tapu Bulu. A slight rearranging of the EVs (60 in Defense) means Tapu Bulu can't OHKO Cradily with 252+ ATK Wood Hammer in Grassy Terrain, and then it dies to Recoil + Sludge Bomb. Or if you're super cute with your movesets, run Poisonium Z to guarantee the OHKO on any Tapu Bulu with Acid Downpour, or guarantee a Z-Gastro Acid on Gengar, bypassing Taunt and Encore.
I may have gone into a bit of a theorymon spiral there. Forgive me.