Dr. Lavaさんのイラストまとめ

3 Decades of Kangaskhan:

With an internal ID number of #2, Kangaskhan is one of the oldest Pokemon in existence. But unlike many of the Pokemon his age, Kangaskhan has remained virtually unchanged.

1. Gen 1 beta sprite, 1990
2. Original artwork
3. Modern artwork

Beta Mantine:

Mantine's typing of Water & Flying makes a lot more sense once you've seen his original design from Gold & Silver's 1997 demo -- which was named Haneei, "Winged Stingray."

1. Demo sprite recreation by @RacieBeep
2. 1997 demo sprites
3. 1999 release version sprites

Beta Bellossom:

In Gold & Silver's 1997 demo, and even in early official artwork, Bellossom was purple. Further reading on why she was later changed to green: https://t.co/fgUXbmjeP1

1. Demo sprite recreation by @RacieBeep
2. G&S 1997 demo sprite
3. Early official artwork

Beta Hitmontop:

In Gold & Silver's 1997 demo, the original Hitmontop design had a bizarre upside-down anatomy. But he was later revised into a design who's just simply standing on his head.

1. Demo sprite recreation by @RacieBeep
2. G&S 1997 demo sprite
3. 1999's final design

Early Nosepass:

Nosepass' original Gen 3 sprite is quite unique compared to his official artwork, and every sprite used in future generations. The most notable differences are his color, general size, and lack of hard edges.

1. Gen 3 sprite
2. Gen 3 artwork
3. Gen 4 sprite

Beta Sneasel:

In Gold & Silver's 1997 demo, Sneasel was originally pure Dark-type and looked much more like a weasel. But he was later revised to Dark/Ice, and made less weasel-like.

1. Demo sprite recreation by @RacieBeep
2. G&S 1997 demo sprite
3. 1999's final design

Beta Espeon:

In Gold & Silver's 1997 demo, instead of high happiness during daytime, Eevee evolved into Espeon via Heart Stone -- a scrapped item also used for Xatu & Politoed.

1. Demo sprite recreation by @RacieBeep
2. G&S 1997 demo sprite
3. 1999 release version sprite

Muneo Saitō -- the PKMN designer most famous for creating Gen 2's Legendary Beasts -- published these creature designs in 2014.

Saitō said she created these monsters for a game, but the designs ultimately went unused... but she didn't specify whether or not the game was Pokemon.

Beta Pichu:

In Gold & Silver's 1997 demo, Pichu was a ball that evolved into Pikachu at level 12. But Pichu was redesigned for G&S's release version, and changed to evolving via happiness.

1. Demo sprite recreation by @RacieBeep
2. G&S 1997 demo sprite
3. 1999's final design

Beta Umbreon:

In Gold & Silver's 1997 demo, Umbreon was pure Poison type. Instead of happiness, Eevee evolved into Umbreon via Poison Stone -- an item that ended up getting scrapped.

1. Demo sprite recreation by @RacieBeep
3. G&S 1997 demo sprite
4. 1999 release version sprite