If your talking about X/Y, Super Training can help. In B2/W2, a Youtuber name tamashii can help. If HG/SS/D/P/P, search EV and traits around this website, such as Gravelers giving high defense and Chanseys giving high hp.
P.S. If you don't have a long attention span, like me, don't bother with EV and training ;).