I had 3 Tyrogues, each evolving into different hitmon-. This proves that most important is training. e.g., when you train Pokémon on Machops, it will gain more attack stat. For defence, train them on Geodudes.
Drugs:
HP Up boosts HP EV
Protein boosts Attack EV
Iron boosts Defense EV
Calcium boosts Sp.Attack EV
Zinc boosts Sp.Defense EV
Carbos boosts Speed EV
Berries:
Pomeg Berry lowers HP EV (and boosts happiness)
Kelpsy Berry lowers Attack EV (and boosts happiness)
Qualot Berry lowers Defense EV (and boosts happiness)
Hondew Berry lowers Sp.Attack EV (and boosts happiness)
Grepa Berry lowers Sp.Defense EV (and boosts happiness)
Tamato Berry lowers Speed EV (and boosts happiness)
Training hold items:
Macho Brace more EV (but lowers speed as long as hold)
Power Weight more HP EV (but lowers speed as long as hold)
Power Bracer more Attack EV (but lowers speed as long as hold)
Power Belt more Defense EV (but lowers speed as long as hold)
Power Lens more Sp.Attack EV (but lowers speed as long as hold)
Power Band more SP.Defense EV (but lowers speed as long as hold)
Power Anklet more Speed EV (but lowers speed as long as hold)