How do i EV train my pokemon?

Give Cottonnee Power Band or Power Belt (Battle Subway). Then go inside Pinwheel Forest with the power Belt attached, beat Sewaddle and Venipede. Both will give 5 defense evs (with power belt attached) or 1 without the belt. Keep track of the evs on notebook paper, and make it so you have 252 defense evs (50 times with belt, 2 without). Then go to route 4 and surf. Have power Band attached. You will battle frillish, which give 5 sp. Defense evs with the band attached. Get to 252 (50 times with band, 2 without). Then you have 4 evs left over for HP. Just beat a few amoongus. You could use 10 iron and 10 zinc at the beginning so it has 100 of each of the defense evs. Then you only need to win 30 times with item, 2 without.