Tauros

Tauros is the most iconic Pokemon in RBY OU, and its presence has been shaping the tier for as long as it has existed. Tauros is undoubtedly the strongest offensive threat in the tier, thanks to its powerful Body Slams and Hyper Beams paired with the coverage moves to hit any Pokemon that resists its STAB moves. This is further enhanced by its high Speed, and therefore high critical hit rate, as well as serviceable bulk. This makes switching into Tauros a very arduous prospect for most teams, as potential checks like Starmie have to fear a sizable chance of paralysis or a critical hit from Body Slam. Other Pokemon with the theoretical physical bulk, such as Snorlax, Cloyster, and Slowbro, can only shrug off Tauros's hits via Rest, leaving them in an exploitable state. Overall, although some special attackers can trade blows advantageously with Tauros, and it has to be very wary of paralysis, its sheer offensive prowess makes it an automatic inclusion on a vast majority of RBY teams.