• English / United States: Rocko
• Japanese / Japan: リーク
• Japanese (Romanized) / Japan: Riiku
• Japanese (TL) / Japan: Riiku

On their way to Higaki City where the Isshu League would be held, Ash Ketchum and his friends were challenged to a tag battle by Pokémon Trainers that were brothers. Rocko is the younger of the two brothers and his older brother is Rocko. They are a bit cocky and overconfident and their dreams don’t always match what is really happening. Together with the earth warrior Mogurew, Rocko controls everything on land. Soren and Rocko and claim to be the world's number one siblings but they realized after facing Ash Ketchum and Cilan that they still had a lot of world to do to actually claim that title.

Rocko and his brother like to use a combination of moves for their attacks and name them appropriate to what the combination produces. This proved to be effective in the tag battle against Ash Ketchum and Cilan until they also decided to use their own combination of moves which ended up overpowering Soren and Rocko. After realizing that they lost in a double battle, the two brother decided to blame each other but Cilan decided to help them out and they graciously accepted that help after being humbled in their double battle.

After doing a tasting compatibility, Cilan suggested that they both needed to have a Pokémon that could cope with opposing Pokémon whose types they were weak to at the time. Cilan took Soren and Rocko fishing to catch a Water Pokémon. Rocko caught a Heigani to give him an all-around land-sea-air collection. Soren and Rocko then began their training work at improving their tag battles with their new water Pokémon by developing new combination moves.