Shinji is a roaming Pokémon trainer from the Sinnoh region. In the saga, Pokémon: Diamond & Pearl, he was first seen in the episode "Two Degrees of Separation", though his full introduction was in "When Pokémon Worlds Collide". He is initially introduced as a power-hungry trainer, that cares little about his Pokemon's feelings, and more for their strength. Because of this, Ash is determined to prove his doings wrong, thus starting their long rivalry. At the conclusion of their last six-on-six battle, Ash finally comes out victorious, thus marking the end of their rivalry.