With the happiness checker you get in the Pokemon center in etera city.
You can make it happy by treating it to spa.
You have to trade with Pokemon heartgold or soulsilver. HAPPY TRADING!
One of the Pokeetches might tell you.
Pearl and Platinum
check your national pokedex check serebii.net :)
check serebii.net
It shows how much the Pokemon is happy with you. In some Pokemon you can evolve it if it has high happiness.
you have to make him happy. hope this helped!
before you ask check your grammar first ^^
if u mean hw many Pokemon on Pokemon dp,the answer is 151 on pearl u can check it on the pokedex in poemon diamond or pearl .
Probably... go check.
itsmells abit