Instructions
Walk or ride your bike around the game world with the Pokémon in your party. As you travel, your Pokémon's friendship level will increase slightly.
Feed your Pokémon vitamins or Pomeg, Kelpsy, Qualot, Hondew, Grepa or Tamato Berries. Each berry or vitamin you feed your Pokémon will boost its friendship level, but it may also affect your Pokémon's stats.
Place your Pokémon at the head of your party, and then talk to special people in the game world. In "Pokémon Black" and "Pokémon White," talk to the masseuse in Castelia City. In "Pokémon HeartGold" and "Pokémon SoulSilver," talk to one of the brothers in Goldenrod City, who will give your Pokémon a haircut. In "Pokémon Diamond," "Pokémon Pearl" and "Pokémon Platinum," get your Pokémon a massage from a lady in Veilstone City. Generally, you can only receive one massage or haircut from each person each day.