'Pokemon Brilliant Diamond and Shining Pearl' Riolu Guide: Where, How to Get and Evolve into Lucario
Riolu is one of the Pokemon that became a fan favorite, as well as one of those Pokemon that was expected to appear in Pokemon Brilliant Diamond and Shining Pearl. Despite the fact that it is hidden in the Sinnoh Region, there are ways to capture this Steel/Fighting-type Pokemon.
Source: gamenguide.com