Originally Posted by Pokemon Trainer Sarah
EV training is actually pretty quick once you have the right items and know where to find the proper Pokemon. It only takes me about half an hour in Diamond. I think I've spent longer trying to breed for a good nature, let alone raising up certain Pokemon to learn moves that I then wanted to pass on to other Pokemon etc. xD
Every Pokemon gives out different EV (Effort Value) points in one of the 6 stats (Attack, Defense, Sp. Atk, Sp. Def, Speed, HP) and if you get 4 EV points you get +1 stat point. So if you battle certain Pokemon over and over you can increase your Pokemon's stats. Here's a guide I wrote if you're interested. I tried to make it as simple as possible because when I was trying to learn to EV train, most of the guides were too complicated xD
Ghastly gives 1 sp attack Ev, haunter gives 2 and gengar gives 3.
I get my level 50 raikou and make him kill 3 gengars, 10 haunters and 15 ghastly's. This is a total of 44 Special Attack EVs. For every 4 Evs (On a pokemon over level 50. under level 50, it is 8 I think) therefore when it levels up it will gain an extra 11 sp attack points. It wont get nall these points on one level up. it will add them gradually. by the time it is level 100 it will have all the stats earnt. This is why using rare candies is bad.