Some Pokémon, like Chansey and Golbat, won't evolve if they're not happy. And how do you make them happy? Leveling them up isn't enough. Actually, it IS enough, but you'd be wasting lots of precious time. To make it happy faster, you must give it drinks, always carry it in your party, level it up, give it haircuts and vitamins and let it hold special items (eg. charcoal if it is a fire Pokémon, etc). In one week or less of regular training, your Pokémon should evolve. Note that some Pokémon like need to be trained at specific times of the day --check the table for more info.

All Pokémon (Not only the ones that evolve by happiness) can be sad or happy. A lady in Goldenrod City, right to the Departament Store, will tell you how much your Pokémon loves you. She'll look at the first Pokémon in your party, say "Oh? Let me see your (Pokémon name)" and then you may get any of these messages:

These Pokémon evolve by happiness:

	POKÉMON	EVOLVES INTO		SPECIAL NOTES
	Pichu	Pikachu		This is a baby Pokémon that hatches from an egg.
	Elekid	Electabuzz		This is a baby Pokémon that hatches from an egg.
	Magby	Magmar		This is a baby Pokémon that hatches from an egg.
	Smoochum	Jinx		This is a baby Pokémon that hatches from an egg.
	Togepi	Togetic		This is a baby Pokémon that hatches from an egg.
	Igglybuff	Jigglypuff		This is a baby Pokémon that hatches from an egg.
	Cleffa	Clefairy		This is a baby Pokémon that hatches from an egg.
	Chansey	Blissey		-NONE-
	Golbat	Crobat		-NONE-
	Eevee	Espeon		Train it during the day.
	Eevee	Umbreon		Train it during the night.

Note that, even if your Pokémon is at the highest happiness level, it will be sad again and dislike you if you don't treat it well (eg. giving it bitter herbs and letting it faint a lot). This doesn't mean that you have to continue giving it vitamins, drinks and haircuts --it'll like you the same if you don't. However, if you give it a bitter herb and then it doesn't like you as much as before, give it a drink, haircut or vitamin and it'll be happy again very soon.