Nostalgic fans may over-romanticize the first generation a little bit. It definitely had its winners like Pikachu, Eevee, Charizard, and Mewtwo, but it also caused a lot of Pokémon to be overlooked and to this day, they are still not popular.
This mostly has to do with design or the fact that the Pokémon are stuck in the middle between evolution lines and thus are not as well-remembered. Some are only memorable due to the anime episodes. In the games though, there was no linear story to serve these Pokémon. Here are ten Pokémon from the Kanto generation that went overlooked back when they were first introduced in the original Pokémon Red and Blue games all the way to this day.
10 Mankey
Mankey was the first monkey-inspired Pokémon. To be honest, most monkey-inspired designs (other than the starters like Infernape and Rillaboom) are often overlooked by fans. As to why this is the case, it may just be that its design is overlooked because it's less interesting than other Pokémon's designs.
There is nothing inherently wrong with Mankey at all but it and its evolution, Primeape, are not often seen in the parties of players or as a plushie in a fans' home collection.
9 Hypno
Hypno is an unsettling anthropomorphic tapir and a hypnotist. It also, like Mankey, perhaps was also inspired by monkeys. Its nose resembles that of a proboscis monkey, but that may be attributed to its features that resemble a tapir.
The original games did not really bless its players with comforting psychic-type designs (until Mew and Mewtwo), and Hypno is a prime example. Except, unlike Mr. Mime, he is overlooked and forgotten instead of used for memes.
8 Graveler
Graveler is one of those poor Pokémon that is overlooked mostly due to the fact that its a middle evolution form. Some fans love Geodude and Golem, but Graveler is not a typical Pokémon that springs into the minds of fans.
Besides being mid-evolution, its design is less satisfying than Geodude and Golem. Its form is bumpy and awkward while Geodude and Golem are smooth and less weird-looking.
7 Tangela
This Grass-type is unfortunate. The creators noticed that Tangela is often overlooked and tried to make it more interesting by giving it an evolution in later games. However, that did not work and proved that this Pokémon really was doomed from the start.
A lot of fans hard trouble wrapping their heads around the design. What is Tangela supposed to be exactly? Vines? A swamp monster? Medusa? What even is under the vines? It is truly hard to tell.
6 Fearow
Fearow's design does not live up to its cool name. It was overshadowed by the Pidgey evolution line in terms of the token bird of the first generation. It looks similar to a great number of predatory birds from hawks to vultures. However, its comb, long neck, and long beak are similar to a chicken combined with a heron. There is just a lot going on.
Despite all of these elements, they somehow culminate into a very boring design. Fearow is definitely the most overlooked bird Pokémon in the entire series.
5 Beedrill
Beedrill was obviously made as a rival or foil for Butterfree due to having a similar evolution line and typing. However, Butterfree turned out to be incredibly more popular. It shouldn't be a surprise either. People tend to prefer the look of butterflies more than bees.
Even when it got its own Mega-form in later games, fans did not seem to care about this Bug-type.
4 Tauros
Tauros is overlooked for a number of reasons. Firstly, its design is pretty boring. Secondly, it has no evolution line or other forms. Thirdly, it's a Normal-type. Normal-types are the most overlooked type of Pokémon in the series, as they are far less exciting than Fire, Water, Dragon, Fairy, and Ghost-types.
The generation after Kanto introduced Miltank to give Tauros a counterpart, and Miltank is also an often overlooked Pokémon.
3 Voltorb
Many nostalgic fans complain that new generations are getting lazier with their designs. However, many seem to forget that Voltorb has existed since the original games. Voltorb is literally just a Pokéball with eyes.
The design is purely at fault for Voltorb and its evolution, Electrode, to be overlooked. It is just hard to connect to this Electric-type with angry eyes. It's almost as if it's self-aware that its design was poor and unpopular.
2 Electabuzz
Future games really tried to get fans to pay attention to this Pokémon, but it was no use. Adding evolutions like Elekid and Electrivire could not save this.
The basis for the design seems to be a combination between a tiger and a Japanese "oni." In theory, that sounds like a cool idea for a Pokémon. Electrabuzz did not make the cut for fans though. Like Voltorb, he is among the most overlooked Eletric-types in the series.
1 Poliwhirl
Like Graveler, Poliwhirl suffers from being the middle evolution. It's not as cute as its Poliwag form and its gloves/mittens are a little unsettling.
It and its evolution line are based on frogs, which is clever. However, Poliwhirl looks more like it could be a mascot and there is a man inside looking out at the world through the suits' nostrils.