Heracross

Mega Heracross is one of the most powerful attackers in 1v1, owing to its sky-high base Attack along with a great set of abilities and diverse movepool. Its great offensive typing lets it muscle past common threats, including Mega Gyarados and Meloetta. Skill Link, accompanied by multi-hit moves like Pin Missile, Bullet Seed, and Rock Blast, lets Mega Heracross fire off high-Base Power attacks, allowing it to get past most Sturdy users like Donphan and Golem and Substitute users like Jumpluff and Whimsicott. Guts allows Heracross to defeat bulky Will-O-Wisp users, namely Mega Sableye. With investment in its excellent bulk, Mega Heracross is able to take hits from powerful attackers like Mega Gyarados, Choice Scarf Porygon-Z, and Meloetta and then retaliate with its strong attacks. Unfortunately, its typing leaves it weak to Fire-, Psychic-, and Fairy-type Pokemon such as both Mega Charizard formes, Victini, and Mega Gardevoir, which are prevalent in 1v1. Its 4x weakness to Flying-type attacks can be exploited by Pokemon such as Mega Pinsir, Choice Specs Celesteela, and other Pokemon that occasionally carry Flying-type moves such as Dragonite, Landorus-T, and Archeops. Mega Heracross also cannot use any viable setup options, as its below average Speed will only open the way to it being OHKOed or 2HKOed if it does not attack immediately.