If you're interested in competitive online battling, you should really look into getting a Ralts that has all perfect IVs (Attack isn't really necessary though). If you don't you are disadvantaged right from the beginning, as everyone else will use perfectly-bred Pokemon against you. It isn't very easy to get perfect IV Pokemon, but there are a number of guides online that can help you get a good Ralts even without a 6 IV Ditto to breed with.
By the way, if you didn't know, you can find your Pokemon's IVs almost exactly in Sun/Moon if you've hatched more than 20 eggs. If you have, talk to the Ace Trainer in the front of the Battle Tree and you will get a "Judge" feature in the PC that shows your Pokemon's IVs graphically.