!!Trivia for ''Red'' and ''Blue'':
* BreakthroughHit: Game Freak made a few games before this like ''VideoGame/MendelPalace'' and ''Pulseman'', but didn't achieve success until ''Red and Blue''.
* KillerApp: This game singlehandedly revived sales for the aging GameBoy, which ended up getting [[GameBoyColor an upgraded version]] the same year as the North American versions of the games.
* SleeperHit: Nintendo of Japan actually said ItWillNeverCatchOn while releasing Japanese ''Red and Green'' and writing it off as a loss. It didn't top the sales charts, but it kept ''selling steady'' in a market where 80% of sales are made in the first two weeks. Game Freak made a few tweaks, released [[UpdatedRerelease Japanese Blue]] and Nintendo got their cash cow.
* UrbanLegendOfZelda:
** There's a rumor that's been floating around since these games came out about a hacked version known as Pokémon Black (not to be confused with ''VideoGame/PokemonBlackAndWhite''), found on a black-painted cartridge. The player is given a Pokémon known as 'Ghost' instead of one of the starters, and it cannot be put into the PC. It attacks opponents with Curse, and if you return to an area after beating a trainer, it's indicated they died as there's a tombstone present. After beating the game, the player character's Pokémon are all gone and the sprite is swapped for an old man sprite. Going back to Pallet Town results in the character being attacked by the spirits of the Pokemon they killed on their way to beating the game, with the character using Struggle until they die. Its existence is questioned, but a ROM like this does exist online. [[http://www.gameinformer.com/blogs/members/b/omegaspartan08_blog/archive/2010/07/30/pok-233-mon-black-a-hacked-game-of-death.aspx Article here]]
** A rumor has always been around that when the games were first released in Japan, loads of little children [[BrownNote got ill and committed suicide]] because of the [[http://www.youtube.com/watch?v=JNJJ-QkZ8cM Lavender Town music.]] Some people thought this was why the music was subtly changed to remove some of the high pitched notes in the American remakes. In reality, the music was changed because people in Japan had been getting headaches from the shrillness of it.
** TheMissingNo ([[TropeNamer or Missing Number]]) has had a number of rumors around it, some said catching it would damage your cartridge others say that it would erase your data.
** There's a truck sprite that only appears once in the game. The only way to see it is to go way out of your way to avoid triggering a certain plot event that closes off the area and returning when you can travel on water. People believed that it had to have been put there for a reason, leading to hundreds of rumors about this thing. As it turns out, it's just a truck.
** Then there's all the rumors about how to catch [[SecretCharacter Mew]]. Humorously, it's actually possible to catch it by abusing glitches, just not the way many of rumors stated.
** Speaking of Vermilion City, the S.S. Anne was said to return there after the player beat the Elite Four so many times.
** Averted in that exploitation of how the game engine processes data will allow you to encounter any monster of your choosing...[[http://bulbapedia.bulbagarden.net/wiki/Mew_glitch including Mew]].
* WhatCouldHaveBeen:
** There once was a [[http://archives.bulbagarden.net/media/upload/7/70/Kensugiart3.png female protagonist]]. She was excluded presumably due to a lack of space for her data and reused for ''[=FireRed=] and [=LeafGreen=]'' as "[[http://bulbapedia.bulbagarden.net/wiki/Leaf_%28game%29 Leaf]]". Her design was used for the character Green (known as Blue in Japan) in Manga/PokemonAdventures.
** Gyarados was originally going to be Water/Dragon, but Creator/GameFreak went with Water/Flying instead because the former effectively had no weaknesses.
** There were originally going to be 190 Pokémon, but they were cut for space. According to [[TheWikiRule Bulbapedia]], all 39 of the cut Pokémon would later end up in ''VideoGame/PokemonGoldAndSilver''. This also explains Ho-oh's ProductionForeshadowing in the anime, as well as the lack of {{Suspiciously Similar Substitute}}s in Generation II, as many of them were made alongside the originals.
** Cutting Pokémon for space is also why Mewtwo is in the Pokedex before Mew; there originally wasn't enough space until the debug tools were removed late into production. Had there been enough room it is conceivable that Mew would have been placed before Mewtwo in the Pokédex.
** During development, the Sevii Islands were considered. But, due to a lack of cartridge space and time limits, they were dropped. They were added in the remakes ''[=FireRed=] and [=LeafGreen=]''.
** It is possible to glitch your way into fighting Professor Oak. His party is effectively identical to your rival except for the starter, which is the one left over after you and your rival have picked. This seems to indicate that somewhere in development, you fought not your rival but the professor himself.

!!Trivia for ''Yellow'':
* RecursiveAdaptation: It's a game based on TheAnimeOfTheGame, and in addition to some {{Canon Immigrant}}s, there are some touch-ups on sprites and Pokémon used in Gym battles: Brock and Misty wear their respective outfits from the anime (in the original games, Brock was [[WalkingShirtlessScene shirtless]] and Misty wore a bikini), and Lt. Surge only uses Raichu in battle, which is what he also did in the anime.[[note]]He used 3 Pokemon in ''Red and Blue'', and the remakes and later games follow this instead[[/note]].

!!Trivia for ''[=FireRed and LeafGreen=]''
* WhatCouldHaveBeen: ''[=LeafGreen=]'' was originally considered to be retitled to "[=WaterBlue=]" for the international releases to match how ''Red and Blue'' were the versions released outside of Japan instead of ''Red and Green''. However, it was ultimately decided that the international releases would be titled the same as the Japanese release, as the ''Leaf'' in the title was supposed to symbolize peace in a world of friendly competition, and they also did not feel like redesigning the box art.