A number of Pokémon now look nothing like their original 2D sprites. When Generation 1 released in Japan in 1996 with Pokémon Red and Green, the sprites lacked the polish needed to fully recreate Pokémon outside the Game Boy. The anime one year later rectified that issue, altering many of the original 151 Pokémon designs to give them more detail and make their anatomy more realistic.

Since then, these designs have further evolved to stay up-to-date with modern sensibilities. The most prevalent example is the natural slimming-down of many Pokémon. Pikachu is the most famous example, with the online fandom clamoring for the original “squidgy” Pikachu rather than the leaner version of the more recent series and games. But Pikachu's design changes throughout Pokémon is not the only example from Gen 1: the Pokémon presented here also look radically different from their original conception.

Related: Pokémon Gen 1 Designs Ruined The Rest Of The Series

Pokédex Pokémon #18 - Pidgeot

An older 2D sprite of Pidgeot is posed next to Pidgeot in its modern design.

Pidgeot’s 2D Pokémon sprite shows it perched, cocked forward like it’s about to eat a bug. Its eyes look almost happy, and the form is kept round. But for all intents and purposes, it really does just look like a big bird. The modern Pidgeot, however, is almost always shown in flight and with a more stern or dignified demeanor, less rounded and more aerodynamic like a bird of prey.

Pokédex Pokémon #31 & #34 - Nidoqueen & Nidoking

Older 2D sprites of Nidoqueen and Nidoking are posed next to their modern designs.

Both Nidoking and Nidoqueen look large and intimidating in their 2D sprites, with their size indicated in the limited format by how big their heads are. But in actuality, both Pokémon are only about 4 feet tall, about as tall as an average 10-year-old.

Pokédex Pokémon #42 - Golbat

An older 2D sprite of Golbat is posed next to Golbat in its modern design.

Golbat’s original Pokémon sprite looks creepy: a completely ludicrous monster that would terrify any unsuspecting spelunkers with its elongated body and probing tongue.

Its modern iteration looks (relatively) composed, keeping the large mouth but looking more menacing than deranged.

Pokédex Pokémon #45 - Vileplume

An older 2D sprite of Vileplume is posed next to Vileplume in its modern design.

As opposed to many other Pokémon that became skinnier, Vileplume actually bulked up in later iterations. Its pose also went from jolly (tipping its flower hat at the player) to more sinister (with the brim of its flower covering one eye). Somehow, that makes all the difference to the intent behind Vileplume’s little smile.

Related: How Pokémon Scarlet & Violet's Gen 9 Designs Compare To Previous Gens'

Pokédex Pokémon #56 & #57 - Mankey & Primeape

Older 2D sprites of Mankey and Primeape are posed next to their modern designs.

Both Mankey and Primeape had angles added to their design, morphing them from hairy blobs into actual primates. Notably, both of them had elbows added to their limbs and their eyes were changed to the “traditional” angled Pokémon eyes. Primeape in particular changed, becoming more of a sphere than a compressed ball shape.

Pokédex Pokémon #66 & #68 - Machop & Machamp

Older 2D sprites of Machop and Machamp are posed next to their modern designs.

Machop looks much goofier in its original Pokémon form prior to 3D, having an almost otter-like snout and oblivious eyes. In its modern form it has been stretched vertically to have more human proportions. Machamp has changed even more drastically though: the original sprite lacks the coloration around its mouth, whether this is some kind of beak or 5 o’clock shadow. Additionally, the crests atop its head are completely spaced out when compared with the modern Machamp whose crests nearly converge.

Pokédex Pokémon #74 & #76 - Geodude & Golem

Older 2D sprites of Geodude and Graveller are posed next to their modern designs.

Geodude actually looks like a dude in his original Pokémon sprite: the bumps on the top of his head resemble a fringe or even pompadour and his thumbs-up reinforces this Fonzie-like aesthetic. Modern Geodude still has this aspect to its personality, but really is just a rock with arms. Golem similarly became a more generic design, turning into a reptilian rock creature that completely differs from its original smiling and doofy design.

Pokédex Pokémon #80 - Slowbro

An older 2D sprite of Slowbro is posed next to Slowbro in its modern design.

Slowbro has always appeared dopey, but in the classic Pokémon sprite it looks positively strange. Something about the perfectly round eye which is disconnected from its snout just looks off. Additionally, the shell on Slowbro’s tail is far larger, so large that it seems to almost incapacitate it. To make this pose work, Slowbro’s tail also needs to be longer than in the modern design.

Related: Pokémon Is Ignoring Its Most Obvious Monster Design

Pokédex Pokémon #91 - Cloyster

An older 2D sprite of Cloyster is posed next to Cloyster in its modern design.

Cloyster’s primary difference is that it's now oriented with the shell opening vertically instead of horizontally. As a result, the large central spike now protrudes from somewhere within the shell instead of emerging from the surface. This change makes Cloyster a little more distinct from the Pokémon Shellder, which was already horizontal to begin with.

Pokédex Pokémon #92 - Gastly

An older 2D sprite of Gastly is posed next to Gastly in its modern design.

Although Gastly kept its trademark mischievous face, its body has completely changed. Originally, Gastly was just a cloud of ominous gas, but ever since Pokémon's Generation 2 it has been given a physical orb-like body from which this gas emanates. Additionally, Gastly’s eyes have been made larger while its fangs have diminished, giving it a baby-like appearance suited to being the first stage of evolution.