Heracross

Heracross's decent Special Defense and high Attack let it take quite a few special hits and fire back hard physically. Furthermore, its key resistances to Fighting- and Ground-type attacks allow it to check Pokemon like Nidoking, Golem, Steelix, and Machamp; when it's healthy, it can safely switch in and check an unboosted Marowak that lacks the uncommon Hidden Power Flying. On top of its high Attack and Special Defense, its Speed is quite good. This allows Heracross to outspeed Exeggutor, Tyranitar, and Umbreon, which all get maimed by Megahorn.

However, Heracross's only prominent STAB move, Megahorn, is resisted by very common types like Flying and Steel. This means that Pokemon like a healthy Zapdos, Skarmory, and Steelix can reliably pivot in and cause trouble for the Hercules beetle, with the threats of Thunder from Zapdos, Drill Peck or Whirlwind from Skarmory, and Roar or Explosion from Steelix, among some more niche moves from these Pokemon. Overall, Heracross can be very effective at shutting down difficult threats throughout the game, but patience must be exhibited when using it, as it needs to wait for some Pokemon that may very well be long-lasting to get KOed or weakened before it can try to clean.