The first time I saw Exeggutor, I was freaked out because of the heads on the trees.
This corelates to the japanese folklore of trees with heads for fruits.
The fruits would have human faces that could smile and laugh.
This tree is called the Jinmenju.
There was a story of the tree yokai that originated from China
where the fruit would laugh as it got ripe and fall off the tree,
even their seeds have faces on them.
This would definitely be the exeggcutes.
We could argue that the exeggutor came before the exeggcute
from their evolving order but fruits, seeds and trees, which one really came first
just like the question is it the egg or the hen?
If you look closely at these two,
they look like the old japanese lanterns called the chochin.
Most inanimate objects
with a lifespan of a hundred years or more would
come to life and be classified as a tsukumogami.
Thus, the two look like a Chochin Obake.
They are lanterns that came to life with one eye and
usually a mouth with its tongue sticking out just frightening people.
They closely resembles the Namazu. From the pokedex entry,
This corresponds to the legend of the namazu who
is a giant catfish that can cause earthquakes.
He lives in the mud and would cause earthquakes when it thrashes about.
Just like the pokedex entry that was stated earlier.
It is believed the origin of the namazu
came from observing the sudden activities of catfish when
an earthquake is about to happen.
Where people from ancient times believed
that there must be a giant catfish that was suddenly active
and was making all the tremors.
This pokemon is just a floating head surrounded by smoke.
It is quite similar to will-o-wisps
but more specifically resembles the sogen-bi in japanese folklore.
A sogen-bi is a fireball yokai that is just a man's head surrounded by flames
that flies in the sky at night.
The story of the sogenbi is that a long time ago,
there was a monk named Sogen.
He was a wicked monk who would steal money from the offerings to the gods.
He managed to do this for years and eventually dies of old age.
But because of his sins, he was then cursed to be a flying head on fire.
From how the jellicent looks, they must be inspired by the Nurarihyon.
You might know the name Nurarihyon from the manga/anime Nurarihyon no Mago.
But there are three different stories of these Nurarihyon,
1 is that it's just an old man that comes to homes and act like he owns it
2 its the leader of all the yokai which is probably where the crowns
on the jellicent's heads came from
and 3 they would "haunt" the sea by bobbing its big head up and down
with the waves on or right below the water,
this is probably where their jelliyfish look came from
and also why it is a water type pokemon.
From the three stories
the physical appearance of the Nurarihyon is that
it has a large head in the shape of a gourde.
Looking at him again, I think the nurarihyon looks like an alien. >.>
These pokemon look like a hippopotamus found a giant shell and
decided to wear it because it feels good.
But the one yokai that it could originate from is
the sazae oni which is translated to the turban shell ogre.
Now the sazaeoni is a shapeshifting yokai
usually shapeshifting to the form of a beautiful women
and would pretend to be drowning in the sea.
There is one legend where it was "rescued" by pirates while in woman form.
That night all the pirates in the ship had their way with her
but she had hers as well by biting off their testicles.
By the end of the night, she had all of the pirates testicles
and desperately
wanting their kintama back, the gave all their treasure to the sazae oni.
They are women lost in snowy mountains as said in the pokedex,
Almost the same like a yuki onna but rather than being lost,
they live in the snowy mountain passes and would prey on people who got lost in the snowstorm.
Their appearance are closely inspired as they are both beautiful,
both female, has pure white skin and piercing eyes.
Legends of the yuki onna mostly involve the yuki onna
falling in love with a man and get married with said man.
But throughout the marriage, the man would start getting suspicious of
whether she is a yokai or human.
The men should've just shut up and take it as it is that they got lucky
getting a beautiful wife who looked young forever but
that's rarely the case.
In short, the marriages always end bad when you marry a yuki onna.