Pokemon "evolution" is a process in which a Pokemon experiences rapid physical growth and manifests into another creature. When a Pokemon evolves, it usually gets taller, heavier, and more powerful although this always its the case. An evolved Pokemon may gain or lose a type and thus changing the way a trainer has to use that Pokemon. Evolution may allow the Pokemon to learn moves it couldn't at a previous form. There are many ways to trigger the evolution process.

The most common way a Pokemon will undergo evolution is by training it and making it gain enough levels. Most Pokemon evolve via this method. When a Pokemon reaches a certain level, it will attempt to evolve. If the player presses B, it will cancel the evolution. The Pokemon will then attempt to evolve each time it gains a level thereafter unless it is holding an everstone.

Stone evolution is when a Pokemon evolves because it was exposed to an elemental stone. There are many stones and they affect a variety of Pokemon. For the Pokemon that evolve via this method, there is no level requirement and the Pokemon can undergo evolution at any time the trainer wises too. Stone evolution cannot be canceled. Pokemon that evolve via this method don't learn any more moves, although there are a few exceptions to this. Some evolutions via the stone method require the Pokemon be of a certain gender for it to work. Because later generations have a limited amount of elemental stones, players may have to choose which Pokemon they want to evolve via this method.

Another type of evolution is the trade method. This requires that the Pokemon be traded to another version for it to evolve. It may require that the Pokemon hold a specific item when it is traded. Once the Pokemon reaches the other cartridge, it will evolve. Like stone evolution, this evolution cannot be canceled.

Two methods of evolution that usually go hand in hand is the time of day and happiness evolutions. Some Pokemon will only evolve if it is a certain time of day. This is usually requires that the Pokemon have a high happiness level as well, which measures how much your Pokemon likes you. This is a stat you cannot see, but several NPCs can tell you your Pokemon's happiness level. When the Pokemon in question maxes out its happiness level and gains one level, it will attempt to evolve. You can cancel this type of evolution by holding B when the Pokemon attempts to evolve. Be aware that most Pokemon that require a happiness level do not need it to be a certain time of day.

Two uncommon ways of evolving a Pokemon is the specific-move technique and the location technique. The former requires that a Pokemon learn a certain move before it can evolve. Once the Pokemon learns this move, it will try to evolve once it gains a level. The latter requires that a Pokemon be trained in a certain area and gain a level for it to evolve.

There are many other ways a Pokemon evolves, but because they only apply to one or two Pokemon they will not be explained here, and will instead be discussed below in the evolution chart.

This chart shows what method is required to evolve a Pokemon that does not need to evolve based on what level it is.

Starting Pokemon	Method of Evolution	Final Pokemon	Starting Pokemon	Method of Evolution	Final Pokemon
#025 - Pikachu	Use a thunderstone	#026 - Raichu	#172 - Pichu	Level up w/max. happiness	#025 - Pikachu
	Use a Moon Stone			Level up w/max. happiness
	Use a Moon Stone			Level up w/max. happiness
	Use a thunderstone			Level up w/max. happiness
	Use a Fire Stone			Use a Shiny Stone
	Use a Moon Stone			Teach Doublehit then level up
	Level up w/max. happiness			Use a Sun Stone
	Use a Sun Stone			Teach AncientPower then level up
	Use a Fire Stone			Use a Dusk Stone
	Use a Water Stone			Use a Dusk Stone
	Attach King's Rock & trade			Attack Razor Fang, level up @ Night
	Trade			Attack Razor Claw, level up @ Night
	Trade			Attack Razor Claw, level up @ Night
	Use a Leaf Stone			Attach Dubious Disk & Trade
	Trade			Level 20 if Atk > Def
	Attach King's Rock & Trade			Level 20 if Atk < Def
	Level up @ Mt.Coronet			Level 20 if Atk = Def
	Use a Water Stone			Use a Water Stone
	Trade			Use a Leaf Stone
	Attach Metal Coat & Trade			Use Dawn Stone on Male
	Use a Leaf Stone			Spare Slot in Party
	Teach Rollout then level up			Level up w/max. happiness
	Attach Protector & Trade			Level up @ Mt.Coronet
	Level up w/max. happiness			Use Moon Stone
	Teach AncientPower then level up			Use a Shiny Stone
	Attach Dragon Scale & Trade			Level up w/max. beauty
	Use a Water Stone			Attach Reaper Cloth & Trade
	Attack Electrilizer & Trade			Use Dawn Stone on Female
	Attach Magmarizer & Trade			Level up w/max. happiness (day)
	Use a Water stone			Level 20 (Female Only)
	Use a thunderstone			Level 20 (Male Only)
	Use a Fire stone			Level 21 (Female Only)
	Level up @ Night w/max. happiness			Level up @ Night w/max. happiness
	Level up @ Day w/max. happiness			Teach Mimic then level up
	Level up @ Moss Rock			Teach Mimic then Level up
	Level up @ Ice Rock			Attack oval stone then level up
	Attach Up-grade & Trade			Level up w/max. happiness
	Level up @ Day w/max. happiness			Put Remoraid in party, level up
	Attach Metal Coat & Trade			Level up w/max. happiness