Tyranitar

Blessed with excellent stats all around, a unique typing, and an insane movepool, Tyranitar is one of the best Pokemon in GSC Ubers. Its ability to check very important Pokemon in the metagame, such as Snorlax, Mewtwo, Lugia, and Ho-Oh, coupled with key attributes like resisting Normal, having access to Curse and Roar, and having few special weaknesses means that Tyranitar fits perfectly on all kinds of teams from offense to stall. The rarity of effective checks to Tyranitar like Machamp and Nidoking in the metagame also means that Tyranitar usually feels less threatened to switch out once it starts boosting with Curse.

However, Tyranitar often finds itself using Roar in conjunction with Spikes support as a way of making progress through teams, as the lack of a powerful STAB move means that it can't fully exploit its gargantuan base Attack stat and thus struggles with the bulky nature of the metagame. Furthermore, many teams are prepared for Tyranitar and have answers to it, such as Celebi, Golem, and Steelix, all of which greatly threaten Tyranitar, meaning a Curse Tyranitar sweep should only be considered when all of its checks are weakened or removed. Lastly, the relevance of Growth + Baton Pass Pokemon like Jolteon and Vaporeon in the tier hurts Tyranitar's ability to reliably check Pokemon it's supposed to, like Mewtwo.