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 :)
It shows how much the Pokemon is happy with you. In some Pokemon you can evolve it if it has high happiness.
check serebii.net
you have to make him happy. hope this helped!
before you ask check your grammar first ^^
If you have the happiness App. for your pokewatch thing... you can see how much your Pokemon loves you (how happy they are).
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.