Nidoqueen

Nidoqueen is the most dominant and centralizing Pokemon in GSC UU. It has an excellent typing and bulk; the former reduces the viability of the Electric types in the tier—such as Ampharos—while also granting immunity to both Toxic and Thunder Wave, and the latter allows it to pose a threat throughout the game with natural longevity. Nidoqueen’s movepool allows it to pack its own countermeasures for its supposed checks, and the ease of keeping Spikes on the field means that it is able to apply pressure to opposing teams fairly easily. Nidoqueen is most certainly the most commonly seen Pokemon, fitting on any playstyle with little or no drawback to using it.