So Cynthia's starter was a Riolu? Looking at how some trainers actually take it upon themselves to look like thier first/favorite pokemon, and how the starter on many 'teams' is usually trained the hightest, I can only assume she did indeed start out with a Riolu.
-The funny clips she wears in her hair=Look just like Lucario's ears (seen from back)
-Lucario being one of her strongest pokemon (game and/or otherwise)
-Maybe it's tradition in Celestic town? I don't recall her ever saying she got her pokemon from Rowan.
You think Riley's from the same town? (the guy who gives you the Riolu egg in D/P)