In ORAS, who is the man with the black Charizard?

Question

spoilers

In the delta episode, before you fight Rayquaza, Steven tells you about a man with a black charizard who fought with him against Rayquaza. Who is he? And what is his story?

Answer 1

Steven is most likely referring to a character that showed up in the Pokemon Mega Evolution Special II named Alain. In the episode he fights Steven's Mega Metagross with his Mega Charizard X(the black Charizard). Both of them encounter Mega Rayquaza later on in the episode. You can find more information here in Bulbapedia and learn his story a little more in-depth but dow here is a small little summary of what he mainly does in these episodes.

Alain (Japanese: アラン Alain) is a recurring character in the Pokémon anime. He is the main protagonist of the side story episodes Mega Evolution Special I and SS031 (Special II). Alain is a Pokémon Trainer seeking to defeat all Mega Evolved Pokémon using his Mega Charizard X. -Bulbapedia

Hope this helped.
Source here <-Basically the link to Bulbapedia

Comments

An answer popped up while writing my own answer.

Answer 2

There is an episode of the anime called 'The Strongest Mega Evolution 2'. Steven and a trainer battle against Mega Rayquaza with his Shiny Mega Metagross and the trainer's Mega Charizard X. So that is who he is most likely referring to.