Riolu evolves into lucario but the only way to get it is to go to iron island and go to the caveang go right then go till you find an elevtor walk on it it will take you down then go to your left then you'll see a guy dreesed in blue he is riley he wants to team up fight your way out then go down another elevator then you split up but he asks you if you want this egg if you have a slot in your party say yes it will hatch into riolu.