Mega Raids in Pokémon Go pit you against a Mega Evolved form of a Pokémon. For Mega Charizard X, you face a formidable opponent, but it will earn you the Mega Energy to transform your Pokémon into a Mega Evolved form. The faster you complete the raid, the more Mega Energy, also known as Mega Candy, to transform them. Here's what you need to know.
Mega Charizard X Weaknesses
Mega Charizard X is a Fire and Dragon type Pokémon, which is different from its traditional Fire and Flying type form. The X variant is weak to Ground, Rock, and Dragon type attacks. You'll probably want to focus on using a Ground or Rock-type Pokémon to destroy it.
Pokémon to counter Mega Charizard X
The best Pokemon you can use against Mega Charizard X include Groudon, Rhyperior, Tyranitar.
Groudon is one of the strongest Ground-type Pokemon you can use. He has a max CP of 4, an attack of 115, a defense of 270, and a stamina of 228. He doesn't have outstanding defenses to fight Mega Charizard, but he should get the job done to do a lot of damage. You want to make sure yours knows about dragon's tail and earthquake. Because Mega Charizard X is weak to Dragon-types, having your Groudon know Dragon Tail means it can reach its weaknesses without being affected by any of X's Dragon-type attacks.
Next up is Rhyperior, the Rock and Ground type Pokémon. It's another great choice to use against him, despite his variety of weaknesses. It has a max CP of 3733, an attack of 241, a defense of 190, and a stamina of 251. Again, it doesn't have the best defenses, but it should be effective against standard X attacks. whether your Rhyperior uses slaps or mud slaps with a wrecker. If you don't have one with his legacy, Earthquake is another great option.
The final optimal choice is Tyranitar, the Rock and Dark type Pokémon. He's in the same boat as Rhyperior in that he has excellent offensive abilities, despite a variety of weaknesses. Hopefully Mega Charizard X can't enjoy it. It has a max CP of 3, an attack of 834, a defense of 251, and a stamina of 207. Ideally, you want yours to know a stone hit and edge. These are unfortunately the top picks that make Tyranitar a good choice if yours knows his heritage. The other fast move choices, Bite and Iron Tail, won't fare well against Mega Charizard X.
If you don't have any of the above, there are several other choices. You can use Garchomp, Golem, Seismitoad, Camerupt, Gigalith, Regirock, Golem (Alola), Reshjiram, Zekrom, Rayquaza, Dragonite or Salamence.