Snorlax

Ever since the dawn of time, Snorlax has been one of the best and most threatening Pokemon in GSC. This holds true even in Ubers, where its absurd power, unpredictability, and hard-to-kill nature are second to none, granting Snorlax a spot on every single competitive Ubers team. Snorlax's sole presence warps the entire metagame around it, forcing teams to pack not only one but multiple answers for it while Snorlax simultaneously checks a wide array of very threatening Pokemon like Mewtwo, Zapdos, and Jolteon. Snorlax is one of the best progress makers in the format with its Curse set, relentlessly forcing its way through the opposition with absurd power and bulk alike, while also having other options like Belly Drum to annihilate defensive or paralyzed teams. Snorlax can do whatever its team needs it to do and does with unmatched game-to-game consistency.

However, because of how metagame-warping Snorlax is, teams pack a lot of answers to it, such as Tyranitar, Golem, and Steelix; all three can phaze Snorlax with Roar, with Golem and Steelix even having access to Explosion to make a huge dent in Snorlax's HP. Other ways of dealing with Snorlax include Explosion from Pokemon like Mewtwo, Mew, and Gengar, all of which can KO Snorlax after some chip damage, although Snorlax can survive Explosion if it has enough Curse boosts. More defensive teams pack sturdy checks to Snorlax such as Barrier Mewtwo, Skarmory, and Lugia. Lastly, Snorlax doesn't commonly run Sleep Talk, meaning that once it's been forced to use Rest or put to sleep with Lovely Kiss or Sleep Powder, foes can use this opportunity to freely take advantage of it, as Snorlax won't have ways to punish them.