I'm probably not the best to give advice for something like this, but I think can lay something out for you.
EVs refer to the "effort values" your Pokemon obtains after winning a battle in the wild. Their stats will increase by the amount of EVs given for each stat every time you level up.
Most of the effects aren't seen if you're using a low level Pokémon. Chances are you only see a slightly higher increase in stats when leveling up.
The game prevents you from having all the 62 stat points Boost at level 5, because at that stage, most Pokemon have HP stats in the 20s and other stats in the 10s.
Moved to the correct thread.