Have they not always been evolving Rivals pokemon earlier then Ash? Also we don't know how long Bel has had Chaoboo. Swinub evolved in DP104. And Charmander evolved into Charmeleon in episode 43, so that is not exactly early on in the anime. Yes Dawn and Ash pokemon evolved rather quickly after they evolved to their second, but both of those where in the middle of their sagas. This is the begging of Unova Saga that is why I just don't see it.