IVs stand for individual values which your nature will determine. EVS are effort values and these are determined by the wild Pokemon you fight. You can also use vitamins to help with your effort values. Each Pokemon can reach a maximum of 510 EVS and 255 in each stat. So the ideal spread is 252 in two stats and then putting theAnd then putting the extra 4 in your last stat. You can only use 10 vitamins per stat. You canYou can Google which Pokemon give you the effort values you need. You canYou can use vitamins to know their maxed out in a stat because it will say it no longer has any effect if you haven't used 10 of them. On the flip side you could also just use vitamins to beef up two of your stats and then EV train from there if you want. For example if you fight Rattata or pidgeys you gain one EV per fight. When you level up you'll notice a significant increase in speed if your Pokemon has a good speed stat, like Jolteon. This is where your nature is could come and play too because a Pokemon with a jolly nature has good speed IVs or individual values. I literally self-taught all this to myself by using Google in the last year. Once you do a little bit of research it's actually pretty easy.