Methods of Evolution
There are a number of methods of evolution, which defines how and when a Pokémon evolves. These can make it slightly harder for some Pokémon to evolve in comparison to others.
By level
Most evolutions happen by a Pokémon achieving a certain level. A Pokémon earns levels by gaining experience points from a battle. A detailed explanation on how experience points work is listed under the "Experience" page.
A Rare Candy can make a Pokémon instantly gain a level, potentially getting the Pokémon one step closer to evolving. If a Rare Candy is used to move a Pokémon to the level at which it would evolve through Experience alone, the Pokémon will evolve; level-based evolution is not discriminatory with respect to how a Pokémon attains its level.
A few exceptions to this method include the Pokémon Daycare and using an Everstone. Pokémon will not evolve regardless of level in the Daycare or by using an Everstone. Therefore, it is safe to say that, for the game's purposes, only Pokémon in a trainer's active party will evolve, if they are not holding an Everstone.
Level evolution is not limited to the normal level at which Pokémon evolve. A Pokémon will try to evolve if it is allowed to at higher levels, but the evolution level commonly listed is the lowest possible level at which the evolution will take place.
Example: Ekans evolves into Arbok at level 22.
By evolutionary stone
Some Pokémon will only evolve after being exposed to an evolutionary stone.
If a Pokémon's next stage requires the use of a stone, then it can be applied at any time, this causing instant evolution.
However, once exposed to an element stone, most Pokémon can no longer learn any more moves by leveling up. There are exceptions to this rule, however, and certain moves are exclusive to the stone-evolved Pokémon.
Example: Nidorino evolves into Nidoking by being exposed to a Moon Stone.
By trading
Some species can only be gotten by being traded to another trainer; as soon as a Pokémon is transferred the evolution process immediately begins. The trade may be facilitated by either a link cable or wireless adapter, or an in-game trade between the player and a non-player character.
A famous mistranslation in the Generation I games suggested that after trading a woman a Raichu, she said that it had evolved. This fueled speculation as to whether or not there would be a third stage to the Pikachu line in Generation II; the third stage was realized in the form of a Baby Pokémon, Pichu.
Example: Graveler evolves into Golem by being traded.
By trading with an item
In the case of some species, it is not enough just to trade them. They must also be given a particular item to hold.
This was introduced in Generation II when some already existing Pokémon were given new evolutionary forms.
Example: Onix evolves into Steelix by being traded when it is holding a Metal Coat.
By happiness
There comes a time when the only way for a Pokémon to evolve is through making it especially happy. This is usually true for baby Pokémon such as Cleffa, but also holds true for some other Pokémon, including Chansey (evolves to Blissey).
Once a Pokémon's hidden happiness stat hits 220, it will evolve on the next level-up.
Example: Golbat evolves into Crobat through being happy.
Others
By Beauty A single Pokémon makes use of a condition stat, the beauty stat. That Pokémon is Feebas. After its beauty stat reaches 170 and the Pokémon gains an additional level, it will evolve into a Milotic.
By Attack & Defense Tyrogue has an odd three-way branched evolution depending on its stats when it reaches level 20.
- Evolves into Hitmonchan if defence is higher than attack.
- Evolves into Hitmonlee if attack is higher than defence.
- Evolves into Hitmontop if defence is equal to attack.
By Personality Value Wurmple's evolution into either Cascoon or Silcoon is based on its personality value, which is dictated when the Wurmple is caught.
By Empty Slot & Poké Ball The method of receiving a Shedinja is perhaps the oddest form of evolution, to the point that it can scarcely be called an evolution. Once a Nincada reaches level 20 it will evolve into a Ninjask, however, if the player has a free party slot and an extra Poké Ball in his/her bag at the time, a Shedinja will fill that slot upon Nincada's evolution.
By Time & Tameness Also, Espeon and Umbreon will evolve depending on the in-game clock. The Eevee it evolves from evolves by happiness.
By Time & Happiness In the fourth generation a new method of evolution was added. A Pokémon will evolve when it is happiest during a certain part of the day. The following Pokémon are known to evolve this way:
- Subomie- Happiness during the day - Roselia
- Lisyan- Happiness during the day - Chimecho
- Riolu- Happiness during the night - Lucario
By Gender Some Pokémon evolve at a certain level but must be either male of female. The following Pokémon evolve using this method :
- Minomutchi♀ - at level 20 - Minomadam
- Minomutchi♂ - at level 20 - Garmeil
- Mitsuhoney♀ - at level 25 - Beequeen
By Gender with hold items Some Pokémon can only evolve when they are a certain gender and are holding an item. The following Pokémon evolve in this way :
- Kirlia♂ - holding an awakening stone - Erlade
- Snorunt♀ - holding an awakening stone - Yukimenoko
By Moves learned Some Pokémon evolve when they level up while knowing a certain move. The following Pokémon evolve using this method:
- Lickitung - Berobelt: Level up knowing the move "Rollout"
- Tangela - Mojumbo , Yanma - Megayanma , and
Piloswine - Manmoo: All evolve when leveled up knowing the move "Ancientpower"
- Aipom - Eteboth: Level up knowing the move "Double Attack"
- Mime Jr. - Mr.Mime , and Bonsly - Sudowoodo: Both evolve when leveled up knowing the move "Mimic"
By area trained at Some Pokémon evolve when they level up in a certain area. The following Pokémon evolve in this way:
