To expand a bit, unless you're using a defensive (such as Ferrothorn) or really slow Pokemon (also Ferrothorn), what you want to focus on are maximum speed, and maximum power in either attack or special attack. Mixed attackers exist, but are tougher to build and use, and normally exist for specific situations that don't really come up anywhere other than competitive play (using mixed Infernape to break the Skarmory+Blissey duo for instance). As you get more experience with EV training you'll know right away which stats to focus on.
Also if you ever aren't sure, or want to check you can also use Smogon's listings. While they aren't perfect for Reborn since the mechanics are a bit different, the Gen 7 lists are usually a safe starting point.