The number of pokemon increases with each new generation. Has there at any point been an in-game explanation, other than the addition of new regions, for the sudden increase in the number of pokemon?

For example : the new Eevee evolutions, addition of newer pokemons in older regions

  • 1
    May be they, you know, breed? Oct 8, 2016 at 9:36

5 Answers 5


I was able to find some explanations in the script, and that's only Gold/Silver/Crystal.

The explanation, overall, seems to be that they were newly discovered:

GOLD! There you are! I needed to ask you a favor. I have an acquaintance called MR.POKEMON. He keeps finding weird things and raving about his discoveries. Anyway, I just got an e-mail from him saying that this time it's real. It is intriguing, but we're busy with our POKEMON research. Could you look into it for us? I'll give you a POKEMON for a partner. They're all rare POKEMON that we just found. Go on. Pick one!

Yo, GOLD! I hear PROF.ELM discovered some new POKEMON.

PIKACHU is an evolved POKEMON. I was amazed by PROF.ELM's findings. He's so famous for his research on POKEMON evolution.

PROF.ELM claims EEVEE may evolve in new and unknown ways.

I am JASMINE, a GYM LEADER. I use the steel-type. ...Do you know about the steel-type? It a type that was only recently discovered.

I'm waiting to see SLOWPOKE's moment of evolution. Through observation, I made a new discovery. A SLOWPOKE with a KING'S ROCK often gets bitten by a SHELLDER.

Some of the new Pokémon are ancient Pokémon that were only recently rediscovered, like the Unown:

The strange POKEMON you saw in the RUINS? They appear to be very much like the drawings on the walls there. Hmm... That must mean there are many kinds of them...

Porygon2, on the other hand, is artificially made:

This manmade POKEMON evolved from the latest technology. It may have unprogrammed reactions.

Here's some related dialogue about new moves:

TM49 contains FURY CUTTER. If you don't miss, it gets stronger every turn. The longer the battle goes, the better it gets. Isn't that great? I discovered it!

Alternatively, consider Bill's explanation, that these Pokémon (and moves) "didn't exist":

You know that POKEMON can be traded, right? My TIME CAPSULE was developed to enable trades with the past. But you can't send anything that didn't exist in the past. If you did, the PC in the past would have a breakdown. So you have to remove anything that wasn't around in the past. Put simply, no sending new moves or new POKEMON in the TIME CAPSULE.

(I like to think that the PC revolutionized Pokémon trade, which in turn lead people to release new types of Pokémon into the wild. That way, you wouldn't find some species because they're not supported by the PC system. I assume the reason you don't find any unsupported Pokémon is because it is essential for a PC to support the local species.)

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    I would take that with a grain of salt. Jasmine says that the Steel-type was recently discovered, but Magnemite had its type changed to Steel. At the end of the day, it's a game. Oct 6, 2016 at 19:46
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    I like that this answer is the only one that looks for answers in the games' test... though the official Pokémon timeline isn't in the same order of the games, so it can't truly make sense in-game. Oct 6, 2016 at 20:25
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    @DanmakuGrazer Magnemite may have had its type "changed", but real world taxonomists change species classification from time to time as well. It would be easy to explain that by saying "We thought it was _____, but now we know it's really ______." Oct 6, 2016 at 21:05
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    @ThaneBrimhall That's a cute explanation, but it suddenly started taking less damage from Ice moves whilst taking more from Fire, so I hope you'll agree with me when I say that it's just a game. Oct 6, 2016 at 21:09
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    @DanmakuGrazer "but Magnemite had its type changed to Steel." We re-classify things constantly IRL when we learn more about them. Pluto was once a planet, and is now a dwarf planet. Thats not really an argument against the new discovery of the steel type.
    – Polygnome
    Oct 6, 2016 at 22:27

There is no in-game answer or any attempt at giving one. Each generation has more Pokémon than the previous one because the folks at Game Freak came up with more of them. The fact that you can complete the National Pokédex could be seen as proof that only those Pokémon exist in the entire world, and no more, but that would be a stretch.

If the games were in chronological order, you could say that every few years there are mass migration events of new Pokémon to older regions, which is somewhat referenced to in games that let you encounter more Pokémon after obtaining the National Pokédex in the form of swarms or items like the PokéRadar, but that's a flimsy explanation full of holes. Just to say it again, there is no in-game explanation to new Pokémon being discovered en masse with every new game.

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    I don't think the fact we can complete the Pokédex proves anything—If you met every single organism that has been taxonomized, would you claim you have met every single form of life on this planet?
    – Setsu
    Oct 6, 2016 at 17:06
  • @Setsu That's not how the Pokédex works, though, and I already said that it's a stretch. What's your point? Oct 6, 2016 at 19:24
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    Your answer assumes that at the release of each game the Pokémon population for that region is completely documented. My point is that just like IRL that may very well not be the case, and it's not mass migration but Pokédex updates for newly discovered Pokémon. However, I agree that the in-game explanation is lacking, and that my conjecture is also full of holes.
    – Setsu
    Oct 6, 2016 at 20:11
  • @Setsu I would call mass migration the massive arrival of new pokémons in a region. Some are very common in new games and nonexistent in former versions of the game, so you can't just call that "pokédex updates" Oct 7, 2016 at 7:55
  • @Setsu Just as a note, you're contradicting yourself. First you talk about "every single organism that has been taxonomized", and then you say that I'm assuming that every region is completely documented. With that aside, let's talk about facts: The Pokédex has empty spots even for Pokémon you haven't seen yet, so we have to assume that the Pokèdex knows about Pokémon it hasn't seen yet. The Pokédex is given to the player so they can gather information on all Pokémon, so we have to assume that the Pokédex doesn't know about Pokémon it hasn't seen yet. Oct 7, 2016 at 11:38

It could be that there are multiple universes within the Pokemon world. In ORAS, it is explicitly stated that at least two parallel universes exist; one that has mega evolution, and one that does not. Perhaps the original game takes place in one where eevee only has three evolutions, there are less types of pokemon, and the absolute horror that is MissingNo. exists.

(Added by Auro) As an annendum, this can extend to every single possible game copy. Because the way the two parallel universes mentioned in ORAS are linked is by... a Link Cable. Just like how, in the pre-DS titles, you could use a Link Cable to connect two game copies of the same generation and therefore transfer Pokémon between games.

  • This is not impossible... IIRC the anime reboots itself every generation or so.
    – Kevin
    Oct 7, 2016 at 5:03
  • What if every color is a separate dimension :o that would explain the slight terrain differences between games of the same generation. That's it, from now on Pokemon is a multiverse in my head!
    – Kevin
    Oct 7, 2016 at 6:50
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    ORAS' Link Cable story has to be the greatest retcon of all time. It explains how Link Battles can have the same trainer avatar appear twice at the same time (or four times for Multi Battles), how come you can get multiple of the same supposedly unique Legendary Pokémon through (inter-dimensional) trading. It even explains why some people get shiny Legendaries - their universe just happens to be that way. Each copy of a game is its own universe within the Pokémon multi-verse. Some universes happen to have more species of Pokémon. Oct 8, 2016 at 14:12

I think this is mainly caused because each generation takes place in a different region. Thats why there are a few pokemon that exist in all region and some are, like in the real world, exclusive to that region.

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    This doesn't really explain why Eevee can suddenly evolve into new Pokémon (E.g. Umbreon and Espeon), unless nighttime didn't exist before the new regions were discovered. I understand from a mechanic point of view, but from a lore, that makes little sense.
    – Draken
    Oct 6, 2016 at 13:29
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    @Draken Nighttime wasn't real until Pokemon Gold/Silver. Fact. Oct 6, 2016 at 13:31
  • @Kaizerwolf Must be due to their two suns I guess ^^
    – Draken
    Oct 6, 2016 at 13:32
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    This is factually wrong, just look at remakes of older games. Oct 6, 2016 at 13:56
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    Eevee also requires happiness to evolve into Espeon/Umbreon, and Red is a horrible trainer whose Pokémon hate him.
    – mm201
    Oct 6, 2016 at 15:31

Simple, they were not discovered yet at the time. Even in real life we are still discovering new animals, mostly in the ocean and in the insect world i suppose, but still.

I also believe in the very first episode of the cartoon series, the pokédex states this: not all pokémon are known, many are still undiscovered, when Ash sees Ho-Oh for the first time in the rainbow.

As for explaining evolutions of older pokémons into new pokémons. The words says it all, evolution.
They simply adapted to a different surrounding/time/climate.

I believe Eevee always needed a fire/thunder/water stone to evolve into a stronger version, but to evolve into Umbreon or Espeon, they only needed the sun or moonlight.
So these evolutions are no longer depended on a variable outside factor.

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    This is your speculation, it's not found anywhere in-game. Consider the new region of Alola. Do you really believe all of the Pokémon living there were previously undiscovered, despite the hundreds of years of civilization in the region? Do you think there's an in-game explanation as to why a Lickitung with Rollout couldn't evolve before gen IV? You can evolve Eevee into Espeon and Umbreon in FireRed and LeafGreen, I don't think your explanation accounts for that. Oct 6, 2016 at 18:02

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