In the Pokemon games "SoulSilver" and "Heartgold," certain Pokemon such a Pichu and Chansey will not evolve unless they like you enough. The degree to which Pokemon like you is based on their happiness level. Keeping a Pokemon active in your party is the easiest way to raise a Pokemon's happiness, but you can do several things that will make them like you faster. The faster they like you, the faster they will evolve.
Capture a Pokemon with a Luxury Ball or a Friend Ball. Pokemon gain happiness more quickly when they are captured by either of these balls. Get a Friend Ball from Kurt in Azalea Town. Purchase the Luxury Ball at the department store in Goldenrod Town.
Keep the Pokemon in the first slot of your team at all times. Pokemon love being in the middle of the action and their happiness will increase automatically. Pokemon gain happiness each time they level up. The Pokemon will lose happiness points it accumulated since its last level if you put it into storage or "day care."
Give your Pokemon the Soothe Bell item to hold. This item increase the rate at which your Pokemon gains happiness points. Find this item in the Pokemon Mansion below Hearthome City
Put the Pokemon in the PokeWalker that comes with all "Soulsilver" and "HeartGold" games and take it for a walk. Your Pokemon's happiness will increase by one point (two points if it is holding the soothe bell) for every 256 steps counted by the PokeWalker's built-in pedometer.
Give your Pokemon lots of vitamins, drinks and certain berries. The vitamins Protein, Calcium, Iron, Zinc, Carbos and HP Up will increase your Pokemon's stats and happiness, but they are expensive. Berries are cheaper. TLook for Kelpsy, Qualot, Hondew, Grepa, Tamato and Pomeg berries. Keep in mind these berries will also reduce you Pokemon's stat's, so it is best to use them when you first get the Pokemon and its stats are already at the minimum levels. Pokemon also love fresh water, soda pop, lemonade and moo milk.
Take your Pokemon for a haircut by the brothers in Goldenrod City. Pokemon love being groomed. Each brother charges differently and gives different results. You can also get free haircuts from Daisy in Pallet Town between 3 p.m. and 4 p.m. every day.
Avoid giving your Pokemon bitter-tasting berries or healing herbs. These cause your Pokemon to lose happiness points. Every time your Pokemon faints in battle it loses happiness.