As many of you probably already know, back in 1996 there was a strategy guide / Pokedex book that never made it out of Japan. In this book, Pokemon are classified mostly by their habitat. Pokemon would once again be classified by their habitat in 2004 with the release of FireRed and LeafGreen, and while most of the habitat names and the Pokemon categorized in them remained from 1996 (ignoring all the Pokemon that didn't exist back then, of course) there were a lot of Pokemon whose classification changed. This is a documentation on those changes. Classifications marked in italics only exist in one version. They were either added in FRLG, or they were cut from the original Pokedex.
Click here for a playlist of DidYouKnowGaming's translations of the original Pokedex.
Grassland
In the original Pokedex, Grassland is noted as housing more Pokemon species than any other habitat. That's still true, but a lot of Pokemon that were once classified as Grassland Pokemon are now classified as something else, though at the same time a lot of Pokemon that used to be classified as something else are now classified as Grassland Pokemon.
Grassland → Urban
Grassland → Mountain
Grassland → Rough Terrain
Grassland → Forest
Mountain
A little over half of the Pokemon originally classified as Mountain Pokemon are still classified as such, though the rest were reclassified as Cave Pokemon. The Cave habitat did not exist in the original Pokedex, and seems to be an offshoot of the Mountain habitat, as only one other Kanto family has been moved there. Oddly, no Mountain Pokemon were moved to the other new habitat, Rough Terrain, despite the them on paper being about as much if not more similar than Mountain is to Cave.
Mountain → Cave
Water's Edge
In the original Pokedex, the Water's Edge habitat is noted for housing Grass-type Pokemon in addition to Water-type Pokemon. Come FRLG, this idea has been abandoned.
Water's Edge → Sea
Water's Edge → Grassland
Water's Edge → Forest
Forest
Most of the Pokemon originally classified as Forest Pokemon are still classified as such.
Forest → Grassland
Sea
A large number of Sea Pokemon were moved to Water's Edge, presumably to fill the space left by the Grass-type Pokemon.
Sea → Water's Edge
Sky
Sky is no longer a classification in FRLG, so every Sky Pokemon is now classified as something else.
Sky → Forest
Sky → Rough Terrain
Sky → Grassland
Urban
The Urban habitat is tied for Grassland as having the most amount of Pokemon reclassified under it, though unlike Grassland, most Pokemon who were already Urban stayed Urban.
Urban → Cave
Enigmatic
Enigmatic is another classification that no longer exists, probably because it's not really a habitat.
Enigmatic → Urban
Enigmatic → Mountain
Enigmatic → Grassland
Extinct
Another defunct classification, fittingly. Considering the Legendary classification was renamed to Rare, I'm surprised they didn't get moved there.
Extinct → Mountain
Extinct → Sea
Legendary (Rare in FRLG)
I just wanna congratulate whoever wrote the original Pokedex for setting up Arcanine as well as they did. Growlithe is the first Pokemon listed in this dex, so when you finally get to the end and see Arcanine, you get a sense of "hey wait a second, that's the dog! That's the fire dog from the beginning!" The book tries to obscure a few other evolutionary families (Magikarp and Venonat) by listing them out of order, but no other family is split across multiple classifications, much less this far apart.
Legendary → Grassland
Legendary → Water's Edge
Click here for a playlist of DidYouKnowGaming's translations of the original Pokedex.
Grassland
In the original Pokedex, Grassland is noted as housing more Pokemon species than any other habitat. That's still true, but a lot of Pokemon that were once classified as Grassland Pokemon are now classified as something else, though at the same time a lot of Pokemon that used to be classified as something else are now classified as Grassland Pokemon.
Grassland → Urban
Grassland → Mountain
Grassland → Rough Terrain
Grassland → Forest
Mountain
A little over half of the Pokemon originally classified as Mountain Pokemon are still classified as such, though the rest were reclassified as Cave Pokemon. The Cave habitat did not exist in the original Pokedex, and seems to be an offshoot of the Mountain habitat, as only one other Kanto family has been moved there. Oddly, no Mountain Pokemon were moved to the other new habitat, Rough Terrain, despite the them on paper being about as much if not more similar than Mountain is to Cave.
Mountain → Cave
Water's Edge
In the original Pokedex, the Water's Edge habitat is noted for housing Grass-type Pokemon in addition to Water-type Pokemon. Come FRLG, this idea has been abandoned.
Water's Edge → Sea
Water's Edge → Grassland
Water's Edge → Forest
Forest
Most of the Pokemon originally classified as Forest Pokemon are still classified as such.
Forest → Grassland
Sea
A large number of Sea Pokemon were moved to Water's Edge, presumably to fill the space left by the Grass-type Pokemon.
Sea → Water's Edge
Sky
Sky is no longer a classification in FRLG, so every Sky Pokemon is now classified as something else.
Sky → Forest
Sky → Rough Terrain
Sky → Grassland
Urban
The Urban habitat is tied for Grassland as having the most amount of Pokemon reclassified under it, though unlike Grassland, most Pokemon who were already Urban stayed Urban.
Urban → Cave
Enigmatic
Enigmatic is another classification that no longer exists, probably because it's not really a habitat.
Enigmatic → Urban
Enigmatic → Mountain
Enigmatic → Grassland
Extinct
Another defunct classification, fittingly. Considering the Legendary classification was renamed to Rare, I'm surprised they didn't get moved there.
Extinct → Mountain
Extinct → Sea
Legendary (Rare in FRLG)
I just wanna congratulate whoever wrote the original Pokedex for setting up Arcanine as well as they did. Growlithe is the first Pokemon listed in this dex, so when you finally get to the end and see Arcanine, you get a sense of "hey wait a second, that's the dog! That's the fire dog from the beginning!" The book tries to obscure a few other evolutionary families (Magikarp and Venonat) by listing them out of order, but no other family is split across multiple classifications, much less this far apart.
Legendary → Grassland
Legendary → Water's Edge