This article is intended to be moved into one of Bulbapedia's main content spaces.
Be mindful that it is still part of a personal userspace. Any content changes should be brought up on the talk page for this article.

Throughout the franchise, the design of some Pokémon received various amounts of changes. Some were temporary, only lasting for one or two games, while others remained for a fair bit longer, causing a disconnect between the video games and other Pokémon-related media.

Overview

The first few generations are interesting due to the sprites having been made before the artwork^[1], rendering the "errors" and other oddities as nothing more than design revisions.

Generation I, for instance, had the original designs tweaked in some places, with Pokémon Blue giving the original roster new sprites, though the back sprites were consistently left untouched. Pokémon Yellow would later update the front sprites once more, this time explicitly basing them after the Pokémon's appearance in the animated series.

In Pokémon Gold and Silver, the sprites for the Kanto Pokémon are mainly based on the contemporary Red and Blue artwork, with some of the new elements tentatively introduced there (such as Nidoqueen's fangs) making a return. Much like with Yellow, Pokémon Crystal later changed a good handful of sprites, using each Pokémon's respective artwork as a basis. This mostly affected the Johto Pokémon, and this time around the back sprites were also updated here and there.

Pokémon Ruby and Sapphire is likely when the artwork was starting to be drawn before the sprites, leaving most of the inconsistencies to be minor in comparison to previous generations. However, many of the Generation I and II Pokémon were either copied directly from Crystal, or based on Red and Green or Red and Blue artwork, as those Pokémon had yet to be redrawn for FireRed and LeafGreen or HeartGold and SoulSilver.

List of sprite discrepancies

Sprite discrepancies due to design revisions

Generation I Pokémon

No.		Game(s)	Reason
001	Bulbasaur	Generation I core series	Originally had round ears instead of triangular ones.
002	Ivysaur	Generation I core series Generation II core series Pokémon Pinball	Originally had a stalk, round ears instead of triangular ones, and two leaves instead of four. Red and Blue changed the ears, while Generation II changed the leaf count on the back sprites only. The Generation I back sprite features a tail, while the Red and Blue front sprite depicts it as bipedal.
003	Venusaur	Generation I core series Generation II core series Generation III core series	Originally had spots, round ears instead of triangular ones, two leaves instead of four, and five petals instead of six. Red and Blue changed the ears and leaf count, while Yellow removed the spots and changed the petal count. The petal count was not carried forward after this, however, as it only appeared on the Silver front sprite before Generation IV. The Generation I back sprite features a tail, while the Generation II, Ruby, Sapphire, and Emerald back sprites feature a rounder petal shape. The five-petal design was reflected in its Red and Blue artwork.
004	Charmander	Generation I core series	Originally had a dorsal ridge. This was reflected in its Carddass artwork.
005	Charmeleon	Generation I core series	Originally had a horn instead of a head protrusion.
007	Squirtle	Generation I core series	Originally had a different plastron design, cheek patterns, and a fluffier tail resembling Wartortle's.
009	Blastoise	Generation I core series Generation II core series Generation III core series Pokémon Pinball	Originally had different cannon cover designs. It was first changed in Yellow, and then to its current design FireRed and LeafGreen, though only on the back sprite.
010	Caterpie	Generation I core series Pokémon Pinball	Originally lacked the pattern on its body.
011	Metapod	Generation I core series	Originally had crosshair-shaped eyes instead of droopy ones.
012	Butterfree	Generation I core series	Originally had differently shaped wings.
014	Kakuna	Generation I core series	Originally lacked pupils. The Red and Blue sprite has its pincers extended, as seen in its Carddass artwork.
016	Pidgey	Pokémon Pinball	Features much longer eyebrows, as seen in its Red and Blue artwork.
019	Rattata	Generation I core series	Originally had a white tail.
020	Raticate	Generation I core series Ruby and Sapphire Emerald	Originally had four fingers on each hand instead of three. This was changed in Yellow, but returned in Ruby, Sapphire, and Emerald.
022	Fearow	Generation I core series	Originally had three talons instead of four.
024	Arbok	Generation I core series	Originally had wave-shaped markings on its back.
025	Arbok	Generation I core series	Originally had a white belly. This was reflected in its Carddass artwork.
029	Nidoran♀	Generation I core series Pokémon Pinball	The Generation I back sprite features different spike placement. Pinball features a tail, as seen in its Red and Blue artwork.
030	Nidorina	Generation I core series	The back sprite depicts it as lacking spikes altogether.
031	Nidoqueen	Generation I core series Gold Crystal Generation III core series	Originally had two rows of spikes. The Generation II and III front sprites feature fangs, as seen in its Red and Blue artwork.
033	Nidorino	Generation I core series	Originally had a tail, as well as a line running through the its inner ear. The back sprite features a dorsal ridge.
034	Nidoking	Generation I core series	Originally had two toes on each foot. The back sprite features two rows of spikes.
035	Clefairy	Generation I core series Gold and Silver	Originally had pawpads, a different ear shape, and a dorsal ridge. Red and Blue changed the ear shape and changed the dorsal ridge to wings, while Crystal removed the pawpads.
036	Clefable	Generation I core series Generation III core series Generation IV core series	The Generation I back sprite features a different ear shape. The Generation III and IV back sprites feature a heart-shaped pattern on its wings.
037	Vulpix	Generation I core series	Originally had different crest designs. The back sprite features a completely different design, while the Red, Green, and Blue front sprite resembles the current one, albeit with two curls instead of three.
038	Ninetales	Generation I core series Generation III core series	Originally had a different crest design. The Generation III front sprites lack differently-colored tail tips, as seen in its Red and Blue artwork.
040	Wigglytuff	Generation I core series Gold Crystal Ruby and Sapphire Emerald Pokémon Pinball	Originally had a white hair tuft instead of a pink one, as well as a stomach pattern that doesn't reach over the mouth. The Generation I back sprite and Red and Blue front sprite have pink eartips. Red and Blue changed the stomach pattern, while Yellow changed the hair tuft and eartips. Some of these traits returned in both Generation II and III.
042	Golbat	Red and Blue	Features a long tongue only ever seen again in spin-off games.
045	Vileplume	Generation I core series	The back sprite lacks white spots.
049	Venomoth	Generation I core series	Originally had a different wing pattern, triangular pupils, and lacked mandibles.
052	Meowth	Generation I core series	The backs of its ears were originally black instead of cream.
053	Persian	Generation I core series	Originally had dark paw and tail accents, and the backs of its ears were black instead of cream.
055	Golduck	Red and Green Red and Blue	Originally had four fingers on each hand instead of three. This was reflected in its Red and Blue artwork.
056	Mankey	Generation I core series	Originally lacked dark paws and had a white tail tip.
061	Poliwhirl	Red and Green Red and Blue Generation II core series Ruby and Sapphire Pokémon Pinball	Was often depicted with gloves instead of mittens, as seen in its Red and Blue artwork.
062	Poliwrath	Red and Green Generation II core series Ruby and Sapphire	Originally had four fingers on each hand instead of three. This was reflected in its Red and Blue artwork.
063	Abra	Generation I core series	Originally had a segmented tail which lacked the dark ring near its tip, as well as a fused back plate instead of separate shoulder pads.
064	Kadabra	Generation I core series	Originally had a protrustion on the back of its head, four fingers on each hand instead of three, and lacked the markings on its stomach.
065	Alakazam	Red and Green	Originally had a Star of David on its forehead, as well as a fused back plate instead of separate shoulder pads.

Sprite discrepancies due to artist error

Generation I Pokémon

No.		Game(s)	Reason
007	Squirtle	Pokémon Pinball	Mistakenly features Wartortle's plastron design.
008	Wartortle	Red and Blue	Features a different plastron design than usual.
011	Metapod	Yellow Generation II core series Ruby and Sapphire Emerald	The Yellow front sprite mistakenly has its eyes placed on its back, as seen in artwork for Pokémon the Series. The Generation II back sprite lacks the crest on its back and features an extraneous line connecting the eyes. The crest was added in Ruby and Sapphire, while the line was removed in FireRed and LeafGreen.
017	Pidgeotto	Crystal	While properly colored in Gold and Silver, Pidgeotto's beak was recolored to brown, but only on the front sprite.
018	Pidgeot	Generation II core series	Mistakenly features Pidgeotto's tailfeathers, as seen in its Red and Blue artwork.
029	Nidoran♀	Red and Blue Diamond and Pearl Pokémon Pinball	The Red and Blue front sprite lacks a horn. The Diamond and Pearl back sprite has a misshapen inner ear. The Pinball sprite lacks whiskers and has spikes in its ears similar to Nidoran♂.
035	Clefairy	Generation II core series Generation III core series Diamond and Pearl Platinum	The Generation II and III back sprites mistakenly have Clefable's tail. The Generation III, Diamond, Pearl, and Platinum front sprites have ears with brown undersides instead of black. This was corrected on Platinum's back sprite and from HeartGold and SoulSilver onwards.
036	Clefable	Red and Blue	Mistakenly has Clefairy's cheek patterns.
037	Vulpix	Red and Green Pokémon Pinball	Has five tails instead of six. Pinball also has two crest curls instead of three. Note that the two curls on the Red and Green sprite are an earlier design and not a mistake.
038	Ninetales	Yellow	Has too many tails.
053	Persian	Red and Blue	Ears are pointy instead of round.
055	Golduck	Crystal	While properly colored in Gold and Silver, Golduck's beak was recolored to light blue.
056	Mankey	Red and Blue	Fur is smooth rather than unkempt.
062	Poliwrath	Diamond and Pearl	Missing its intestines.

List of model discrepancies

Model discrepancies due to design revisions

No.		Game(s)	Reason
031	Nidoqueen	Pokémon Stadium series Pokémon Colosseum Pokémon XD: Gale of Darkness Pokémon Battle Revolution	Features fangs, as seen in its Red and Blue artwork.
040	Wigglytuff	Pokémon Stadium series	Stomach pattern doesn't reach over its mouth, as seen in its Red and Blue artwork.
062	Poliwrath	Pokémon Stadium series Pokémon Colosseum Pokémon XD: Gale of Darkness	Has four fingers on each hand instead of three, as seen in its Red and Blue artwork.
142	Aerodactyl	Pokémon Stadium series Pokémon Colosseum Pokémon XD: Gale of Darkness Pokémon Battle Revolution	Eyes are red instead of green, as seen in its Red and Blue artwork.
144	Articuno	Pokémon Stadium series Pokémon Colosseum Pokémon XD: Gale of Darkness Pokémon Battle Revolution	Eyes are red instead of brown, as seen in its Generation I artwork. In the Pokémon Stadium series, it also has a blue beak and talons, as seen in its Red and Green artwork.
201	Unown H	Pokémon Stadium 2 Pokémon Colosseum Pokémon XD: Gale of Darkness Pokémon Battle Revolution	Originally was asymmetrical in design.

Model discrepancies due to artist error

No.		Game(s)	Reason
125	Electabuzz	Pokémon Stadium series	Has six fingers on each hand.
168	Ariados (Shiny)	Pokémon Battle Revolution	Completely lacks a Shiny coloration.
191	Sunkern	Pokémon Stadium 2 Pokémon Colosseum Pokémon XD: Gale of Darkness Pokémon Battle Revolution	Has green irises.
201	Unown (Shiny)	Pokémon Stadium 2	Completely lacks a Shiny coloration.
207	Gligar	Pokémon Stadium 2 Pokémon Colosseum Pokémon XD: Gale of Darkness Pokémon Battle Revolution	Claws are white instead of pink.
208	Steelix	Pokémon Colosseum Pokémon XD: Gale of Darkness Pokémon Battle Revolution	Eyes are blue instead of red.
431	Glameow	Generation VI core series	Ears are at an incorrect angle. This is notably the only model changed between Generations VI and VII.