In a handful of newer playthroughs that I do, I don't find myself needing to grind very often, at least not until near the end of the game. Sometimes i'll find myself picking it up before a big battle, like, say, the Team Flare Secret HQ, but in most challenges I do that and before the Pokémon League are one of the only times that I find myself needing to grind much in XY.
Nuzlockes and Wedlockes are the exception, obviously.