Jynx

Jynx is a good sleeper in the RBY Ubers metagame, able to immediately pressure opposing teams with the fastest Lovely Kiss in the game. It has very powerful STAB moves in Blizzard and Psychic that give it good coverage to hit Rhydon, Exeggutor, and Zapdos for good damage while pressuring Chansey with Special drops. Jynx has decent Speed and a decent Special stat to back up its Lovely Kiss and strong STAB moves. Being an Ice-type even allows it to pivot into and wall Ice Beam Chansey, Mewtwo, and Slowbro before they set up with Amnesia.

However, Jynx has very low Defense, taking heavy damage from most physical attacks. It is slower than several notable Pokemon such as Tauros, Gengar, Zapdos, and Mew. Jynx can also end up as setup bait for Slowbro, Mew, and the dangerous Mewtwo after it has put something to sleep and gotten its freeze, requiring very careful use after landing both statuses. Overall, Jynx finds its role as a strong sleep- and freeze-inducing lead with good matchups against standard Psychic-type leads.