The tricky parts of the game can only be figured out by older players. It involves too much math for little kids. I'm not downing younger players, though. My brother is only eight and he's really good with evolutions and type advantages/disadvantages. I've told him about EV training, which confused him a little until I explained the main point of it. The show is more childish, in my opinion, but if you are older and you're watching it, you can get more out of it like shipping. Younger ones don't look for that too much, either that they only see the obvious heterosexual pairings.
Edit: Battle Frontier isn't exactly the easiest thing for younger players, in my opinion. It's fun, yes, but if you're actually really set on winning, older players can think of a better strategy or can go EV train and defeat it quicker and more easily than a younger player. The games are enjoyable for all ages, yes, but some things are just easier to grasp depending on your age. My brother tries to fly through the game and I'm more intent on raising good Pokemon to trade to my storage Emerald/Diamond.