Evolution plays a huge role in Game Freak’sPokemonseries; serving not only as a means of making a Pokemon stronger but also obtaining a brand new form of it. Back in the days ofPokemon Red and Blue, evolving a Pokemon by trading it or using an evolution stone was about as complicated as it got, while each Pokemon typically had no more than two additional forms (if any).
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These days, however, some of the evolutionary lines found throughout thePokemonseries have become incredibly complicated, with multiple branches and increasingly bizarre methods of inducing evolution added into the series. Not all of them are quite beyond comprehension, but there are perhaps one or two of them that would have left even Charles Darwin scratching his head.
Updated July 20, 2025, by Tom Bowen:The ninth Generation of Pokemon games brought with it over one hundred new Pokemon, many of which belong to complicated evolutionary lines. Some require players to use a particular move a certain number of times, while others depend on which of the two Gen 9 games the player opted for. They join a host of pre-existing Pokemon with complex evolutions and equally bizarre genetic lines. Many of these Pokemon are able to evolve into multiple forms, with the outcome typically tied to when, where, or how the evolution is triggered.
12Wooper
There’s perhaps an argument to be made that Wooper is a little similar to the likes of Vulpix and Meowth.All three Pokemon have regional forms, which in turn have their own unique evolutions. However, where Vulpix and Meowth simply evolve into regional versions of their regular second-stage forms, Paldean Wooper instead evolves into a brand-new Pokemon.
When a Johtonian Wooper reaches level 20 it will evolve into the loveable and dopey Quagsire, but there is no such thing as a Paldean Quagsire. Instead,Paldean Wooper will evolve into Clodsire at level 20; an equally dopey yet very different-looking Pokemon to Quagsire. It’s also a Poison/Ground-type rather than a Water/Ground-type, meaning that it behaves very differently in battle.
Wooper Evolutions
11Sneasel
Wooper is not the first Pokemon whose regional form has its own evolution, far from it, in fact. Another example can be found in the 2022 titlePokemon Legends: Arceus, in whichHisuian Sneasel and its brand-new evolution Sneasler made their debut. The latter even ended up playing an important role in the game, with players able to use it to climb mountains.
Interestingly, the methods for evolving Sneasel and its Hisuian counterpart are actually incredibly similar, though there is one key difference. To evolve Sneasel into Weavile, players will need touse a Razor Clawduring the night. To evolve Hisuian Sneasel into Sneasler, players will again need to expose it to a Razor Claw, only this time, they’ll need to do so during daytime hours.
Sneasel Evolutions
10Toxel
There werequite a few Baby Pokemonadded to the Pokedex following their introduction inPokemon Gold and Silver. After Gen 4, however, there was a rather long gap without any new additions. In fact, it would not be until Gen 8 and the introduction of Toxel that players would finally get a new baby Pokemon to raise; and it’s quite a unique one at that.
Which form of Toxtricity a player’s Toxel will evolve into upon reaching level 30 is entirely dependent on the Pokemon’s nature. Bashful, Bold, Calm, Careful, Gentle, Lonely, Modest, Mild, Quiet, Relaxed, Serious, or Timid Toxels will evolve into the Low Key Form of Toxtricity. If the Toxel has an Adamant, Brave, Docile, Hardy, Hasty, Impish, Jolly, Lax, Naive, Naughty, Rash, Sassy, or Quirky nature though, it will instead evolve into the Amped Form.
Toxel Evolutions
9Rockruff
In many ways, Rockruff is like a simpler version of Eevee, although without anywhere near as manyevolutionary branches. The rock-type Pokemon has three possible evolutions and these are determined by the time of day that it evolves. All three of them effectively lead to the same Pokemon, although Lycanroc has three different forms which each have their own distinct appearances and move sets.
Its Midday form can be obtained by reaching level 25 during the daytime and its Midnight form is acquired by instead evolving Rockruff at night. Lycanroc’s third and final form requires Rockruff to have the Own Tempo ability and then evolve between either five and six PM in the Gen 7 games or seven and eight PM in Gen 8.
Rockruff Evolutions
8Tyrogue
There were plenty of choices to be found in the first generation ofPokemongames; starting, of course, with whether to play through theRedorBlueversion of the game. Players next had to choose their starter Pokemon and then later, whether they wantedthe kicking machine that is Hitmonleeor the powerful puncher Hitmonchan. This choice became a little less straightforward, however, when the second generation ofPokemongames arrived.
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Not only did Game Freak introduce the baby Pokemon Tyrogue, but also a third evolutionary form in the shape of Hitmontop. Rather thanusing evolutionary stonesor something simple to determine what Tyrogue would evolve into though, the developers instead tied it to the Pokemon’s attack and defense stats. If Tyrogue’s attack is higher than its defense when it reaches level 20, it will evolve into a Hitmonlee, but if its defensive stat is higher it will instead become a Hitmonchan. The only way that it can evolve into a Hitmontop is if its attack and defense stats are equal.
Tyrogue Evolutions
7Pichu
Having started out with a fairly straightforward evolutionary line, Pikachu’s evolutions have become increasingly complex since the days of Gen 1. In the original games, players could evolve their Pikachu by using a Thunder Stone, which would see it turn into a Raichu. This all changed in Gen 2 though, with the introduction of baby Pokemon.
A pre-evolved form of Pikachu known as Pichu was added to the games, with players needing tolevel up their Pichu with the highest possible friendship statin order to evolve it into a Pikachu.Gen 7 made things even more complexwith the addition ofAlolan Raichu, which can only be obtained by evolving a Pikachu with a Thunder Stone while in the Alola region.
Pikachu Evolutions
6Poliwag
When Poliwag first arrived in Gen 1, its evolutionary line was fairly simple; with the tadpole-like Pokemon evolving into Poliwhirl at level 25 and then Poliwrath when introduced to a water stone. That changed a little though with the introduction of an additional evolutionary form in Gen 2.
Now, rather than having to evolve Poliwhirl into a Poliwrath, it’s possible to instead evolve it into the pure water-type Pokemon Politoedby trading Poliwhirl with a friend. It’s not quite that simple though, as the Poliwhirl also needs to be holding the King’s Rock item at the time of the trade.
Poliwhirl Evolutions
5Mime Jr.
Back whenPokemonfirst broke onto the scene, there was no Mr. Mime evolutionary line to speak of; only Mr. Mime himself. That all changed in Gen 4, however, with the introduction of Mime Jr. Even then though, it was far from complex; with the Baby Pokemon evolving into his adult form by leveling up while knowing Mimic.
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Where things started to get a little complicated was in Gen 8 withthe introduction of a Galarian formof Mr. Mime and an additional evolutionary stage. Mr. Rime can only be obtained by getting a Galarian Mr. Rime up to level 42, while Galarian Mr. Mime himself can only be acquired by evolving Mime Jr. in the Galar region.
Mime Jr. Evolutions
4Wurmple
While Gen 1’s moth and butterfly-like Pokemon each have their own distinct evolutionary lines, their Gen 3 equivalents are instead evolved from the same Pokemon. Bizarrely though, there’s no way for players to tell which branch of the evolutionary line they’ll be taking until the first evolution takes place.
Whether or not Wurmple will evolve into a Silcoon or a Cascoon depends on the Pokemon’s personality value; a stat that players have no way of seeing without hacking the game. Thankfully, this evolution takes place at level 7, meaning that they at least won’t have to wait too long before finding out. The new Pokemon will evolve again just three levels later, so obtaining Beautifly and Dustox isn’t actually that difficult, although it may require a few attempts.
Wurmple Evolutions
3Slowpoke
When it comes to Pokemon evolutionary lines that have grown in complexity over the years, few can rival Slowpoke’s. In Gen 1, it simply evolved into a Slowbro when it reached level 37. The introduction of Slowking in Gen 2 changed things up a little though, with players now able to trade their Slowbro while holding a King’s Rock to instead obtain this new, slightly superior form.
Upon their arrival in Galar, however,players were greeted with a Galarian form of Slowpoke; which in turn meant Galarian forms of each of its possible evolutions. Rather than evolving via the same methods, however, players instead need to use one of two newly added consumable items in order to trigger the change. Using a Galarica Cuff on a Galarian Slowpoke will cause it to evolve into Galarian Slowbro while using a Galarica Wreath will instead lead to it becoming a Galarian Slowking.
