IV's are simple values that all pokemon have for each stat. They have a maximum of 31, and the better the IV, the better the stats. For example, my Weavile has straight 31 IV's for all stats. Generally, you want good IVs because these IV's give you an edge over other pokemon. Say if two Weavile went against each other. If they were both Jolly, and had 252 Speed EV's, and Weavile 1 had a 30 Speed IV, while Weavile 2 had a 31 Spd IV, then Weavile 2 would win. I do have a well IV's Blaziken, so if you would like I can attempt to IV train from that.