>>16938909Remember, Salamence does not have a secondary STAB to work with. Dragon/Fire has near-perfect coverage, meaning Megazard-X really has no reason to run any non-STAB attacks other than EQ or Thunderpunch (which Salamence and Garchomp wish they had). Garchomp can't use Dragon Dance, either. Actually, Garchomp only gets Fire Fang, which Charizard has by level up, so your movepool argument kinda falls apart.
Both Salamence and Garchomp are 4x weak to ice moves, while Megazard-X is free from any compound weaknesses. Ice attacks in general are more common than Earthquake, which seemed to have fallen out of favor last generation compared to Fighting moves, at least as far as non-STAB usage. This generation's reaffirmation of the power of priority (especially of the avian affiliation) and the addition of a new anti-Fighting type might change that somewhat, though Xzard still has the advantage of not being weak to any priority move, as well as a neat little neutrality to Fairy. Mega Charizard X cannot be crippled by a burn, either.
