How do you increase your Pokemon's stats in Pokemon Diamond?

Answer 1

you level up the Pokemon or give them stat boost you can buy at the Pokemon super mart like protein,carbos,iron ect

You can also increase there stats by getting EV-enhancing items at the battle frontier for 16 battle points each the items are.

Power weight: increases hp

Power bracer: increases attack

Power belt: increases defense

Power lens: increases special attack

Power band: increases special defense

Power anklet: increases speed

You can make your Pokemon stronger in stats by making them hold these.

They really do work I have a Dusknoir that has really high hp and they are usually supposed to have low hp.

You find these items at battle frontier on the bottom left shop near the battle castle.

To gain battle points I suggest going to battle hall since you get more battle points the longer you keep a winning streak make sure you use a Pokemon with a wide variety of types of attacks to make sure you don't get stuck at a Pokemon like shedinja.

You can also make a Pokemon hold one of these while breeding them so the egg has a higher stat for which item you chose it to hold.