Behold the most overrated Pokémon in existence! Though to be fair, a giant fire-breathing dragon (Despite not actually being a Dragon type) pretty much taps the dopamine in every child's brain upon seeing it. The fact Gamefreak kept giving the OG Fire starter mega evolutions and G-Max forms certainly helped. The former gimmick having returned has certainly given Charizard its time in the sun again (For the Y mega quite literally), and love it or hate it, you cannot deny the impact it has had on the franchise both commercially and now competitively.
Draco Drum
Ability: Blaze/Solar Power
Item: Sitrus Berry
Nature: Jolly
EVs: (HP 4) (Attack 252) (Speed 252)
Moves:
Belly Drum
Flare Blitz/Temper Flare
Acrobatics
Earthquake
Set Details:
Every set that regular Charizard can use can be done better by its megas, with one notable exception. By combining Belly Drum with a Sitrus Berry, Charizard can become a surprise physical sweeper that has access to power that surpasses even its X mega. After the set up we have Flare Blitz or Temper Flare as your Fire STAB with the former offering great power at the cost of hefty recoil or Temper Flare which is weaker but has no durability issues. Acrobatics also pairs well with this set since you quickly consume your held berry allowing it to reach 110 base power STAB easily with no drawback. Finally we have Earthquake for coverage. Invest everything into attack and speed, and your ability comes down to either chancing upon Blaze activating fire power below 1/3 or Solar Power if you can reliably get sun support.
Black and Blue and Dread All Over
Ability: Blaze -> Tough Claws
Item: Charizardite X
Nature: Jolly
EVs: (HP 4) (Attack 252) (Speed 252)
Moves:
Dragon Dance
Flare Blitz/Temper Flare
Dragon Claw/Scale Shot
Earthquake
Set Details:
It's dark, it's edgy, it's finally a Dragon type, it's Mega Charizard X! Fanfare out of the way, this is a pretty straightforward physical sweeper set that relies on Dragon Dance for additional speed and power alongside your newly obtained Tough Claws ability for that nifty extra 30% attack for contact moves. Flare Blitz offers immense power but costly recoil, or you could play it safer with Temper Flare. Your newfound Dragon typing calls for a Dragon type move, which either goes to Dragon Claw for consistency or Scale Shot for inconsistent power but guaranteed extra speed boosts at a defensive cost. Finally there is Earthquake for coverage. Max attack and speed once again, and enjoy the carnage while you act like an edgelord.
Solar Saurian Sweeper
Ability: Blaze -> Drought
Item: Charizardite Y
Nature: Timid
EVs: (HP 4) (Sp. Attack 252) (Speed 252)
Moves:
Fire Blast
Solar Beam
Scorching Sands
Air Slash/Dragon Pulse/Focus Blast/Weather Ball
Set Details:
A scorching sun special sweeper. Arguably the strongest Drought setter right now, Mega Charizard Y offers both reliable sun support while also being one of the best abusers of this weather. The harsh sunlight jacks up the power of Fire Blast to new levels and turns Solar Beam into a single turn move you can spam against the Water, Rock, and Ground types. Scorching Sand offers important coverage against opposing Fire types trying to take advantage of the sun and may even burn surviving non-Fire targets. Finally, the last slot is a matter of what you want to be prepared for. Air Slash is a nifty secondary STAB option with flinch chance, Dragon Pulse is a good answer to Dragon types that can eat your Fire Blasts and Solar Beams, Focus Blast is unreliable but could pull through in a clutch, or you can opt for Weather Ball which is a more accurate supplement to Fire Blast and may give you new coverage options if your opponent tries to shut you down by setting up Rain, Sand, or Snow. Invest everything into special attack and speed and become the draconic incarnation of Helios.
Now if only Gamefreak could give more love to Pokemon other than Charizard...