treat it like you would treat a friend, basically. don't let it faint and feed it stat raising items (ex. carbos, iron, zinc) you can also give it a soothe bell to hold, which makes your Pokemon more friendly.
well, you have to build a strong bond with your Pokemon. For example, if you wanted a blissey, it is required that you get it's happiness to go up. battle other Pokemon with it, and you might might...
They way you get happiness is when you battle with the Pokemon all the time! An example is my Jolteon, I used to battle with it all the time. Which had it's happiness sky rocket. Which they will...