Friendship
Generation I
In Generation I, Pokémon Yellow introduced a prototype version of the Happiness value that would later be used in future generations. Pikachu will follow your main character throughout the game. You can turn and look at Pikachu at any time to gauge its loyalty to you. Its expression will range from angry to ecstatic depending on how happy it is. At its peak, Pikachu will jump up and down.
Pikachu's Happiness level will rise when it gains a level.
It will drop when it is put into Bill's PC, or faints. Trading it will reset its Happiness rating.
It is relatively easy to make Pikachu happy compared to Pokémon in future generations.
Happiness is not recorded for any other Pokémon in Generation I, aside from Pokémon Yellow's starter Pikachu.
As far as gameplay goes, Pikachu's Happiness only truly affects whether or not the player can acquire a Bulbasaur in Cerulean City.
Generation II
Generation II saw the introduction of Happiness for all Pokémon for any trainer. It is a single byte, a value between 0 and 255 inclusive. Wild Pokémon have the same starting Happiness value as in Generation III, or about 70 (27%). Pokémon that are hatched from eggs get a default Happiness value of 120 (47%).
In Generation II, another concept was introduced: evolving through Happiness. The following Generation II Pokémon evolve through Happiness:
- Togepi --> Togetic
- Pichu --> Pikachu
- Igglybuff --> Jigglypuff
- Cleffa --> Clefairy
- Eevee --> Espeon (if evolves in the daytime) OR Umbreon (if evolves at night)
- Chansey --> Blissey
- Golbat --> Crobat
Happiness-based evolutions occur when Happiness reaches 220.
Happiness is typically modified in the following ways:
- Walking (+1)
- Grooming, older brother (+3)
- Stat modifiers (+5)
- Gaining a level (+5)
- Energypowder (-5)
- Heal powder (-5)
- Energy root (-10)
- Revival herb (-15)
Generation III
Happiness in Generation III is a value between 0 and 255. Wild Pokémon have their own base happiness, which is typically 70 (about 27%) for non-legendary first stage Pokémon, but not always. If a Pokémon hatches from an egg, its initial happiness ignores the base happiness value and is set to 120 (about 47%). When a Pokémon is still in its egg, its happiness value is ignored (as there are no aspects in the game that apply happiness to eggs) and the happiness value is used as a decrementing step value that triggers the egg hatch when it reaches zero.
Happiness evolutions occur when happiness reaches 220 (about 86%).
Happiness is modified in the following ways:
- Gaining a level (+2)
- Using Soothe Bell (+1 for each other event)
- Walking 256 steps (+1)
- Stat modifiers (+2)
- Pokémon FireRed/Pokémon LeafGreen: Grooming (+3)
- Pokémon Emerald only: Certain berries (+5)
- Energypowder (-5)
- Heal powder (-5)
- Energy root (-10)
- Revival Herb (-15)
