There should be a guy hanging around at the Pokémon Center of Kiloude City. He's got a pale-looking skin, green outfit, and purple hair (sort of like Bugsy, one of the gym leaders of Johto). If you talk to him, he will introduce himself to you and immediately rate the first Pokémon of your party, telling you what its potential is. Before the conversation ends, he will give you a few statistics. These stats are supposed to be your Pokémon's IVs. (: Another way to check IVs is by getting yourself into a certain type of battle, but I'm not quite sure how that works.