Edit: Oops, text wall...got to into that description haha.

IV - the pokemon's Individual Value. When you first obtain your starter or any other/catch it has a random set of IVs for each stat (0-31). 0 being the absolute worst while 31 being the best. If you ever hear someone talk about "perfect IVs it usually means all stats are at 31. All legendaries in games now have 3 stats set at being 3 perfect IVs, though if you're lucky it could be higher. All Pokemon in the friend safari have a set 2 perfect IVs or higher. That's why so many people want a Ditto safari to farm. I only got a perfect 4IV Ditto from it. Though a friend sent me a 6IV Japanese later on I've been using; better chance at shinies while breeding for IVs now

EV - basically mean Effort Value. You can have a total maximum of 510 Effort Value points on a Pokemon. A stat max can only have I believe 202 EVs on a single stat...I'll have to recheck that. EV training basically the Pokemon to gain more points towards the EV trains stats. If you EV trained say a Blissey, it's got two perfect IVs, those being in HP and Def. if you EV trained those Blissey has a better chance of hiring the maximum hp limit and defense limit. If it has the nature that benefits HP or Def then it has an even better chance.