Pokemon: The Origin

Synopsis

Red finally arrives at the Pokemon League on the Indigo Plateau, where he battles against and defeats the Elite Four. However, he discovers that Blue has beat him to the title of Pokemon League Champion. In order to obtain the title for himself, Red challenges Blue to a battle. The match soon boils down to a showdown between Red's Charizard and Blue's Blastoise, with Charizard managing to win out. They are then visited by Professor Oak, who immortalizes Red and his Pokemon in the history of league champions. Afterwards, Red continues his journey and manages to catch all 149 known Pokemon. Upon returning home, however, Red learns that Blue was badly beaten by a mysterious Pokemon not listed amongst those Red encountered. Recalling a diary he encountered during his travels, Red deduces this to be an artificially made Pokemon named Mewtwo. After receiving advice from Oak about the stones Fuji had given him, Red goes to confront Mewtwo, finding him to be incredibly powerful. As both Red and Charizard become determined not to give up, the stones they received, revealed to be Mega Stones, begin to glow, resulting in a Mega Evolution that evolves Charizard into Mega Charizard X, allowing them to defeat and capture Mewtwo. Upon realizing there is still a Mew to be found, Red becomes determined to fully complete his Pokedex, unaware that Mew is right outside.

(Source: Wikipedia)