where can i get female riolu/lucario in pokemon platinum

[second]

where can i get female riolu/lucario in pokemon platinum?

[Zidarose]

To get a female, you would need some luck either when you receive your egg from Riley or by breeding your Lucario with Ditto.

The gender is determined very early on, if I understand right, when you receive the egg. To manipulate it, you would need to save before Riley makes his offer or before you take the egg from him.

It is important to note that there is only a 12.5% chance of getting a female Riolu/Lucario, so expect some work regardless of the method used.