Happiness

The happiness of your Pokémon determine certain things including when some Pokémon will evolve and the power of Return/Frustration. Happiness is based upon a number, but you cannot see this number in your game.

Base Happiness
All Pokémon have a level of happiness that they start out with when you catch, hatch, or recieve them in a trade.
(Move your mouse over the image to see the Pokémon's name)

Base Happiness	Pokémon
0
35	and all evolutions
70	All Pokémon not shown start here
140	and all evolutions

If a Pokémon has been hatched from an egg, it will automatically start with a Base Happiness of 120 regardless of its species.

How do I make my Pokémon happier?
Everytime you perform one of the following actions below, your Pokémon will gain points towards its happiness.
At higher happiness levels, these actions will give you less and less points, so you'll have to do them more often.

Method	Happiness Points
Walk around with it in your party	+1 for every 256 steps
Level it up	+5 each lvl at 0-99 pts. +3 each lvl at 100-199 pts. +1 each lvl at 200+ pts.
Feed it Vitamins (ex. Calcium)	+5 per item at 0-99 pts. +3 per item at 100-199 pts. +2 per item at 200+ pts.
Have Daisy from Pallet Town groom it (FR/LG only)	+3 at 0-199 pts. +1 at 200+ pts.
Have lady from Veilstone City groom it (D/P only)

Also, catching the Pokémon in a Luxury Ball will double the amount of happiness it gains when you perform the above actions. Attaching the item Soothe Bell to it will increase the rate of happiness by 50%.

How do I make my Pokémon unhappy?

Method	Happiness Points
The Pokémon faints in battle	-1 each time
Feed it Energypowder or Heal Powder	-5 at 0-199 pts. -10 at 200+ pts.
Feed it Energy Root	-10 at 0-199 pts. -15 at 200+ pts.
Feed it Revival Herb	-15 at 0-199 pts. -20 at 200+ pts.

Also, trading your Pokémon to other versions resets its happiness back to its base level.

Happiness Levels
When your Pokémon reaches certain levels in happiness, certain things will happen. In order to check on its happiness, you can go to Verdanturf Town if you're playing Ruby/Sapphire/Emerald, Pallet Town if you're playing Fire Red/Leaf Green, or Hearthome City if you're playing Diamond/Pearl. In Verdanturf, a girl will check on your Pokémon; in Pallet Town, Daisy will do so.

49 pts. or below - Frustration has strongest power (102)
Daisy's comment: I don't like the way it glares at you. Could you try to be a little nicer to it?
Verdanturf Girl's comment: It's very wary. It has scary viciousness in its eyes. It doesn't like you much at all.

70 pts. - Most Pokémon's happiness start here
Daisy's comment: It's not quite familiar with you yet.
Verdanturf Girl's comment: It's not very used to you yet. It neither loves nor hates you.
Hearthome Girl's Comment: It's feeling neutral toward you. It's up to you to change that.

220 pts - Pokémon that evolve through happiness will evolve upon the next level-up.
Daisy's comment: It looks very happy.
Verdanturf Girl's comment: It seems to be very happy. It obviously likes you a whole lot.

250 pts and above - Return has strongest power (102)
Daisy's comment: It couldn't possibly love you any more than it does now. Your Pokémon is happy beyond words.
Verdanturf Girl's comment: It adores you. It can't possibly love you any more. I even feel happy seeing it.
Hearthome Girl's Comment: It simply adores you! Why, I feel like I'm intruding!

What Pokémon evolve through happiness?

Golbat ------> Crobat
Eevee --------> Espeon (Day) or Umbreon (Night)
Chansey ---> Blissey
Togepi -------> Togetic
Pichu ---------> Pikachu
Cleffa--------> Clefairy
Igglybuff ----> Jigglypuff
Azurill -----> Marrill
Budew ------> Roselia
Buneary Lopunny
Munchlax ---> Snorlax
Riolu Lucario (Day)
Chingling Chimecho (Night)