Many fans of Pokemon can easily enough pick out which of the 800+ creatures are inspired by real-world animals, like the gecko-like Treecko or owl-like Noctowl. Some Pokemon are even inspired by objects like keyrings and sandcastles, but those are usually easy to distinguish. Some Pokemon have more mythic origins, and draw design and lore inspiration from animals and beings out of legend.
With so many of the titular creatures from Pokemon out in the in-game world, it makes sense that a lot of them would be based off of less common muses. Some Pokemon draw inspiration from Japanese yōkai, or yokai, that some Western players may not be as familiar with. Pokemon and Nintendo both originated in Japan, so it makes sense that the creators would draw on their own legends. Yokai are supernatural spirits or monsters, and some are more malicious whereas others just want to cause mischief, or can even bring good luck. Here are some Pokemon, many of them Psychic and/or Dark types, that people may not know are inspired by Japanese yokai.
Slowking and Slowbro
Both these pink Water/Psychic-type Pokemon evolve from Slowpoke, with Slowbro being the automatic evolution if the Pokemon reaches level 37. Slowking is only obtainable if the player trades a Slowpoke while it's holding a King's Rock. Both evolutions carry a large Shelder in a symbiotic relationship, with Slowking wearing it on its head, and Slowbro wearing it on its tail. Slowking and Slowbro's relationships with Shellder draw a parallel with a yokai known as sazae-oni, which is a shapeshifting yokai that look like large turban snails. These yokai are more malicious, and sometimes disguise themselves as a beautiful woman in order to trick sailors, similar to the legend of the singing sirens from Greek myth.
Munna and Musharna
These Unovan Psychic-types are heavily associated with sleep and dreams, and even have the sleep condition-inducing moves Yawn and Hypnosis, as well as the HP-sapping move Dream Eater. That last move makes these Pokemon's association with one particular yokai very clear: baku, a creature that eats dreams. Baku was supposedly made out of the leftover parts of other animals, but it looks especially tapir-like. Munna and its evolution Musharna aren't shaped like any particular animal, although some people have drawn parallels between their shape and floral pattern with Japanese incense burners. However, there is something distinctly tapir-like about both Pokemon's snouts, and their dream-devouring motif is hard to ignore.
Mawile
The yokai Mawile was based on is called futakuchi-onna, or "two mouthed-woman," and one of the most distinctive features of Mawile is the giant second mouth on the back of its head. Although the Pokemon can be male or female, the fur around its legs looks like a skirt, and the Dark-type adds onto the feeling of maliciousness. The futakuchi-onna is a type of yokai who was once a human but was cursed to become a malevolent spirit, like the rokurokubi, a woman with a supernaturally long or detachable neck. As of Gen 8, Mawile has several moves that make use of its second, sharp-toothed mouth, like Bite and the Stockpile/Swallow/Spit Up combo. It also has some Fairy-type moves like Fairy Wind and Play Rough that allude to its deceptive and literally two-faced nature.
Dusclops and Dusknoir
Dusknoir is one of the creepiest Pokemon according to in-game lore, with its Pokemon Sword and Shield Pokedex entries claiming that it can steal and devour people's souls. Dusclops and its evolution appear to draw inspiration from a few different sources, some of them being yokai. One is chōchin-obake, or "paper lantern ghost," which gives these two Pokemon their round shape and single eye, although this cyclopean nature may also come from hitotsume-kozō, which looks like a bald child with a single large eye. Most likely, the Pokemon are a combination of multiple one-eyed yokai, and they even appear to take inspiration from the Western spiritual figure known as the Grim Reaper, which escorts lost souls just as Dusknoir does (according to its Pokedex entry).
There are tons of yokai-inspired Pokemon, including Nintetails, Golduck, Exeggutor, and Banette. Japanese mythology is a rich source for anyone to easily spend hours delving into, and these are just some of the most visually compelling Pokemon inspired by these fascinating spirits and monsters.