you can't- you have to catch pikachu and evolve him
I am not sure, but you can evolve a riolu from a riolu egg that Riley gave you in Iron Island. Sorry if this is a bad answer!
Riolu is a Fighting type pokemon.
Catch a Riolu and evolve Riolu.
Riolu
Riolu is 4 generation Pokemon. You can get egg only in Pokemon Diamond and Pearl
happiny and riolu
happiness and daylight
yes u can get riolu in Pokemon heart gold and soul silver you catch him or her in the safari zone and you can catch lucario in the safari zone two.
Yes it is possible.
Anywhere that you can catch Riolu. Shiny Pokemon can appear anywhere and anytime; with a 1/8192 chance of one appearing.
You haven't made it far then. You can catch old pokemon. Yes, you can catch Riolu in the challenger's cave after you beat the elite 4. He's rare though.
You cannot do that unless you have Pokemon rangers 2. So if you want another riolu you have to get Pokemon rangers 2.