In Pokemon diamond and pearl, how many ev points do you need to add 1 stat point to overall stat?

Question

I defeated 6 Machoke (2 ev atk) with Mamoswine and yet his attack only increased by 6 points when he leveled up. Please explain why?

Answer 1

Every 4 points.  EV gain is not immediately obvious so keep on working away (say that you maxed out all the evs, you would only find that the attack points would have all been added when you reached level 100).  Max ev in each stat is 255, but put those 3 points on something useful!  Max ev gain in total is 510, so don't waste all the points!  You know when you've finished when you get an effort ribbon so check every now and then.  Also, vitamins will also make EV gain easier, each vitamin gives 10 evs in the mentioned stat.  You can only gain a maximun of 100 evs in each stat via vitamins, so you'll have to do the rest.  Pokerus is also REALLY useful, it doubles EV gain like the macho brace so its great for a trainer

These items boost the number of EVs gained per battle with a pokemon in their

respective stat.

Power Ankle: Boosts Speed EVs

Power Band: Boosts Special Defense Evs

Power Belt: Boosts Defense EVs

Power Bracer: Boosts Attack EVs

Power Lens: Boosts Special Attack EVs

Power Weight: Boosts HP EVs

Answer 2

For every 4 points, the stat increases by 1 point. If you defeated 6 Machoke, then you should have only gotten a 3+ points in attack. You might of given it Protein or have done other stuff to increase the stat by 6 points during level-up. The level of your Mamoswine also changes  the stat increase. For further information on EVs and EV training, I suggest you go to: http://www.serebii.net/games/evs.shtml