Mewtwo is the clone of Mew. This means that Mew existed before Mewtwo.

So why is Mew numbed 151 in the Pokedex and Mewtwo 150?

  • 1
    Never thought about that before, probably because i haven't watched Pokemon in a while. Too many seasons. Mar 1, 2014 at 23:04
  • It's been ages since I last watched Pokemon, so maybe I forgot, but - does the anime ever reference Pokedex numbers? I don't seem to remember that happening.
    – senshin
    Mar 2, 2014 at 9:26
  • 1
    @senshin Yeah I was thinking the same thing. That this is a video game question as opposed to an anime question.
    – krikara
    Mar 2, 2014 at 9:53
  • @senshin, krikara. late as it may be. Chapter 17 of pokemon adventures mentions Mew as number 151.
    – Dimitri mx
    Aug 18, 2017 at 8:49

5 Answers 5


Because Mew wasn't intended to be one of the 150 pokemon you can acquire through normal gameplay. It was the "mystery" Pokemon, no one was supposed to know its existence. It was only attainable by

  • Nintendo events
  • Gameshark
  • Game glitch

So yeah it makes no sense, but, if Mewtwo had been #151, your Pokedex in Red and Blue would have a gaping hole in it at #150.

Mew was considered extinct when the Pokedex was made. But as Mewtwo was alive and known, he was placed first. Later, Mew's resurrection of his species in Emerald by a scientist meant they could now get his info for the Pokedex. Mew's original form in the Pokedex was actually just "???" Pokemon, who could learn any move.


Let us be reminded that the Pokemon franchise started off from video game, and its initial release was Pokemon Red and Green in Japan in 1996. So Mew's very first appearance can only be in Japanese Pokemon Red and Green.

According to Bulbapedia, in the Trivia section of Mew:

  • Mew was a little-known secret when Pokémon Red and Green were first released in Japan. Even Nintendo was not initially aware that Shigeki Morimoto had programmed it into the game.

  • In an interview with Game Freak and Creatures, Inc. in Nintendo Power issue 134, Shigeki Morimoto revealed that he created Mew two weeks before game development was finished.

Quoting from the interview which is cited in the Bulbapedia page:

Morimoto: We put Mew in right at the very end. The cartridge was really full and there wasn’t room for much more on there. Then the debug features which weren't going to be included in the final version of the game were removed, creating a miniscule 300 bytes of free space. So we thought that we could slot Mew in there. What we did would be unthinkable nowadays!

Ishihara: This is in spite of being told after debug ended that you weren’t to tamper with even a single bit! (laughs wryly)

Iwata: What’s the point of going through all the trouble of the debug process if you’re going to go and fiddle with the game afterwards…? I’d venture that this all came from Morimoto-san’s mischievous nature.

Morimoto: Well, it was a prank that everyone right up to Tajiri-san was in on. But even though Mew was in there…

Iwata: …It wasn't actually supposed to appear in the game, right?

Morimoto: Right. Unless we could think about any good opportunity to do so, the existence of Mew wouldn’t have been revealed to the public. It was left in there in case it was suitable for some post-launch activity. But if there wasn’t anyone among ourselves who wanted to use it, I thought it would be fine to just leave it as it was.

Iwata: Mew could very well have ended up never appearing in the game.

Morimoto: Right. But then due to an unforeseen bug, Mew ended up appearing in some players’ games. It looked like we planned all of this, but that wasn’t the case. So although it caused all sorts of problems to many concerned, fortunately enough it ended up having a positive effect.


Iwata: That’s how the “Legendary Pokémon Offer”8 came about.

8 The “Legendary Pokémon Offer” was announced in the April 1996 edition of CoroCoro Comic. Twenty winners would be selected who could send their game cartridge in so that the Mew data would be uploaded onto it. There were approximately 78,000 entrants.

From the quotes above, it is evident that Mew was not supposed to appear in the first generation. It was only programmed in at the last minute, occupying the space of debug feature.

The interview hinted at the fact that Mew was added after the debug process had ended, so swapping the number of Mewtwo and Mew at that point would have been disastrous, since Mewtwo had an event in the Cerulean Cave, and its stats, move set, flavor text, ... record would have to be swapped with Mew's. Appending a record at the end was safer, especially when the record was not supposed to be used at all during the normal game play.

  • 2
    I wish I could upvote this more than once +1
    – Mansuro
    Aug 5, 2016 at 7:36

Mew was a Pokemon long forgotten (10,000 years ago in the series). So in this sense, when a Pokemon is found or discovered that is not in the records, it will be added after its discovery. Mewtwo was created using Mew DNA, thus Mewtwo came before Mew in the records


Ok aside from the what is stated in the video games, if I remember correctly, Mew was more of a myth and thought to be at the very most extinct. Dr. Fugi, who had already been working on cloning, went in search for any remains of Mew. After having found what he thought to be fossilized Mew remains he began to clone it for the leader of Team Rocket, Giovanni (having to tweak the DNA a bit). The name Mewtwo comes from the way Dr. Fugi named all his clones (Bulbasaurtwo, Charmandertwo, etc) although Mewtwo was the only one to survive. It was only after Mewtwo escaped that the original Mew was discovered to not be extinct.

Editor's note: I had to do some digging to get something more solid than my own and similar vague souvenir. I know the answer is a bit old but I figured I'd share my findings since the comment inquiries for sources.

The information above comes from comes from the first 2-3 minutes of the 10-minutes long short Myutsuu To Ai / Mewtwo and Amber (Ai in Japanese), more commonly known in English as The Birth of Mewtwo, which was shown on Japanese television the first time Mewtwo Strikes Back aired.

The whole short (specifically the last 7 minutes) was rated PG-13 due to the somewhat troubling/controversial topic(s) for children and thus, 4Kids Entertainment decided not to include more than the G-rated first 3 minutes intro (under the title Mewtwo's Origin) in the theaters and DVD releases of Pokémon: The First Movie - Mewtwo Strikes Back, which was enough to grossly explain to the Western public about the origins of Mewtwo.

The full ten-minute short is now available in the DVD release of Pokémon: Mewtwo Returns.

The entire short's transcript is available at multiple locations online, the specific website that sent me on the right track was: http://www.lchr.org/a/23/et/amberkins.html

  • 2
    Do you maybe have source material to back up this statement ?
    – Dimitri mx
    Sep 1, 2016 at 13:23

I would say that Mewtwo is number 150 instead of 151 because Mew was said to be extinct and forgotten, but that's just my answer. Plz don't sue me.

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