How do you get Riolu in Pokemon Platnium?

You can't get Riolu directly in Pokémon Platinum. Riolu is a pre-evolution of Lucario, and you need to evolve a Riolu to get a Lucario.

Here's how to get Riolu in Platinum:

1. Find a Shiny Bidoof: Bidoof is a common Pokémon found early in the game. Shiny Pokémon are rare, but you can increase your chances by using the Shiny Charm.

2. Trade the Shiny Bidoof: You need to trade your Shiny Bidoof to a specific NPC at the Pokémon Mansion in Eterna City. This NPC will then give you a Riolu.

Important Note: You can only obtain one Riolu per game using this method.

Let me know if you have any other questions!