As if the world of Pokémon wasn’t mysterious enough in the original Red, Blue, and Yellow releases (and Green, if you’re from Japan), the developers decided to sneak in one more Pokémon at the last minute, and one that was so absolutely secret that not even Nintendo was aware of it. That Pokémon was, of course, Mew, and although it was mentioned within in-game texts in regards to Mewtwo and its origin, Mew itself was about as untouchable a secret as a secret could be back then. Incapable of being caught my normal means, this Pokémon would actually need to be given to you at official, Nintendo-sponsored Pokémon events.