Rioulu is a baby Pokemon so it cannot breed with any Pokemon.
Riolu is 4 generation Pokemon. You can get egg only in Pokemon Diamond and Pearl
no but you get the riolu egg in iron island
riolu
happiny and riolu
A Riolu, which can evolve into a Lucario.
You do not find an egg that doesn't hatch into happiny or riolu. You must find a girl and boy Pokemon (or girl and ditto or boy and ditto Pokemon) and put them in the daycare, and they may make an egg and allow you to get an egg that isn't happiny or riolu (unless that was the pair you made the Pokemon for).
If it is a starter
no
No, but Lucario can.
riolu
If you mean Riolu, here's a tip: you can get an egg from Riley when you hit the Iron Island first time. When the egg hatches, you will get Riolu.
A Riolu egg can be obtained from Reiley within the Iron Island