>>20903080I was about as perfect as it could be in Gen 4, with only Empoleon and Shedinja resisting.
Gen 5 brought about eternal Rain, but Swift Swim+Drizzle got banned, and then it was left to fend 5/8 turns against Ferrothorn.
Gen 6 brought about Fairies, two of which resist both of its STABs, on top of nerfed rain and preexisting Ferros. It gained a niche crit set that requires speed setup.
At this point, Ludicolo is a better Rain sweeper than Kingdra is (though, that isn't saying too much considering it was always number 2 Swift Swimmer). Sad times for Kingdra.