Charizard

Mega Charizard X is one of the premier offensive threats in the metagame thanks to its access to two amazing boosting moves in Dragon Dance and Swords Dance, reliable recovery in Roost, solid Attack and Speed, Tough Claws, and an amazing STAB combination that enables it to threaten nearly everything in the tier. Its typing and decent bulk let it find several setup opportunities against Pokemon that it easily forces out, such as Volcarona and Mega Scizor. It is also blessed with a crucial coverage move in Earthquake, enabling it to threaten Pokemon that resist its STAB combination, such as Mega Diancie and Heatran. Its solid Speed stat lets it revenge kill Pokemon like Tapu Lele and Kyurem-B. After a Dragon Dance, Mega Charizard X can outpace most of the unboosted metagame, such as Greninja, Tapu Koko, and Mega Alakazam, and Choice Scarf users like Landorus-T and Tapu Lele, while Swords Dance turns it into one of the deadliest wallbreakers in the tier, letting it 2HKO Slowbro with +2 Dragon Claw and OHKO Landorus-T at +1 after Stealth Rock. However, it is held back by its 4x weakness to Stealth Rock before Mega Evolving and is susceptible to being worn down by Flare Blitz recoil and contact punishers like Garchomp, Ferrothorn, and Rocky Helmet users like Landorus-T. As a result, it requires entry hazards to be removed from its side of the field to truly flourish.

Mega Charizard Y

Mega Charizard Y shines in OU as the best sun setter in the tier thanks to its ability Drought and a premier attacker with its strong coverage options, allowing it to rip through offensive teams. Not only does it take advantage of its own sun thanks to its high Special Attack, Fire typing, and access to Solar Beam, Mega Charizard Y also enables a wide array of different Pokemon, be it Synthesis, Moonlight, and Morning Sun users or Fire-types seeking to fire off boosted versions of their STAB moves and to face weakened Water-type moves. Moreover, Mega Charizard Y is blessed with an extensive movepool, allowing it to run strong options such as Focus Blast to hit Mega Tyranitar and Heatran, and it has access to Roost to improve its staying power, which meshes well with its immunity to Spikes and Toxic Spikes provided by its Flying typing. Finally, its ability Drought is a formidable tool against teams relying on weather other than sun to function such as rain and sand, allowing Mega Charizard Y to stop some threats seen in those structures such as Mega Swampert and Excadrill. However, its Fire / Flying typing is also a curse; Stealth Rock, a move present on virtually every team, cuts Mega Charizard Y's HP in half once it enters the field. Additionally, its average Speed makes it prone to being easily revenge killed by offensive threats such as Mega Diancie and Tapu Koko. Despite Mega Charizard Y being a hard hitter, it is still walled by common balance picks such as Toxapex, Chansey, and Mega Latias.