If you're finding the game too easy, you could try turning off the Exp. Share so that you gain experience more slowly. The Exp. Share mechanic is great if you're using a large number of Pokemon (I used it to rotate new Pokemon into my team as I caught them and get them up to speed, which made it easier to use more than six Pokemon than in the past), but if you're using only a few Pokemon, you'll become overleveled far too quickly. (I recall being at level 36 by the second gym badge, before I diversified my team a bit more, and it felt kind of ridiculous.)
Super training allows you to train Pokemon in particular stats. If you haven't played since the first couple of gens, I don't know if you know about EVs, but they're different from the stat experience system used in gen I and II. In both games, Pokemon have what you can think of as base genes ("DVs" in gens I/II, "IVs" since then), and those determine how high your Pokemon's stats could hypothetically get, relative to the species maximum. In XY and ORAS, IVs range from 0 to 31 (31 high). EVs, or effort values, are points you can put into each stat to enhance it. In gens I and II, every Pokemon could reach its maximum stats (given its particular DVs) in all stats, by gathering something called stat experience. In the newer games, however, you can't max out all of your stats; instead, you can decide on how you want to distribute the 510 total EV points the game gives you. You can put up to 252 EVs into each stat, and for every 4 EVs in a stat, you will gain 1 point in that stat at level 100. When you battle, different species of Pokemon give you different allocations of EVs, usually depending on their strengths (e.g., a Pokemon that specializes in speed may give you 1, 2, or 3 speed EVs). If you play the game normally, you'll end up with a somewhat random allocation of EVs based on the Pokemon you encountered, which, while fine for in-game play, won't do for competitive battling.
Using super training (or other methods, but super training is the easiest one conceptually), you can EV train Pokemon as you see fit from the start of your journey. One super training point = 1 EV. Whether you want to super train or not is up to you. You don't really need it for in-game, and the Pokemon you train probably won't be competitive anyway without breeding them later for better IVs, but if you want to try it out, there's no harm in doing so. I wanted to try it when I first got X, so I super trained my Kalos starter, Kanto starter, and fossil, and I don't regret it (though I don't use them competitively). If anything, though, super training your Pokemon may make the game easier, if that's a concern.