It seems to be simply based on general cartoonish ghosts, cats, or the Cheshire Cat and possibly on a distorted shadow of a human being like shadow people.
Gengar and Gangar are possibly a shortening of doppelgänger, a double of a person, which is fitting for a Pokémon with a habit of pretending to be a person’s shadow. The kanji 幻 maboroshi can also be read as gen and is used in words meaning phantom or illusion. There is also a striking pronunciation similarity to the Danish word genganger, a term for ghosts found in Scandinavian folklore.
No: 094
English Name: Gengar
Japanese Name: Genga
Generation: 1
Type: Ghost, Poison
Species: Shadow Pokémon
Abilities: Cursed Body
Evolution: Gastly > Haunter > Gengar
Morty’s Gengar floating through the air
Gengar is a dark purple, bipedal Pokémon with a roundish body. It has red eyes and a wide mouth that is usually curled into a sinister grin. Multiple spikes cover its back, and it has large pointed ears. Its arms and legs are short with three digits on both its hands and feet. It also has a stubby tail.
As Mega Gengar, a portion of its body sinks into the ground. The lower portions turn a more reddish purple, and a third eye appears on its forehead. This new unblinking eye is oval, yellow, and allows it to see into other dimensions.[1] The spikes on Mega Gengar’s back are more numerous and pointed. Additionally, spikes appear on its hands and tail. Its ears are now considerably longer and project backward.
Gengar has the ability to hide perfectly in the shadow of any object, granting it exceptional stealth. However, Gengar’s body acts as a heat sink. Its presence cools the temperature of the surrounding area by nearly 10 °F (5 °C), because it absorbs the warmth. In addition, Gengar possesses the ability to fly through the air, as demonstrated in the anime.
Gengar is very mischievous, and at times, malicious. It enjoys playing practical jokes and casting curses, such as pretending to be one’s shadow, then behaving erratically. When the quarry notices, the Gengar takes delight in its victim’s terror. However, Gengar has been known to be loyal to a Trainer who treats it well. Gengar lives in shadows of rooms, caves, and dark places where shadows form. It is especially fond of urban areas such as cities and back alleys, but only during the night.
POKEDEX ENTRIES
Pokemon Red: Under a full moon, this Pokémon likes to mimic the shadows of people and laugh at their fright.
Pokemon Blue: Under a full moon, this Pokémon likes to mimic the shadows of people and laugh at their fright.
Pokemon Yellow: A Gengar is close by if you feel a sudden chill. It may be trying to lay a curse on you.
Pokemon Stadium: Appears to attack people who get lost in the mountains. Said to be the culprit behind shadows that laugh in the moonlight.
Pokemon Gold: It steals heat from its surroundings. If you feel a sudden chill, it is certain that a Gengar appeared.
Pokemon Silver: To steal the life of its target, it slips into the prey’s shadow and silently waits for an opportunity.
Pokemon Crystal: Hiding in people’s shadows at night, it absorbs their heat. The chill it causes makes the victims shake.
Pokemon Stadium 2: It steals heat from its surroundings. If you feel a sudden chill, it is certain that a Gengar appeared.
Pokemon Ruby: Sometimes, on a dark night, your shadow thrown by a streetlight will suddenly and startlingly overtake you. It is actually a Gengar running past you, pretending to be your shadow.
Pokemon Sapphire: Sometimes, on a dark night, your shadow thrown by a streetlight will suddenly and startlingly overtake you. It is actually a Gengar running past you, pretending to be your shadow.
Pokemon Emerald: Deep in the night, your shadow cast by a streetlight may suddenly overtake you. It is actually a Gengar running past you, pretending to be your shadow.
Pokemon FireRed: It is said to emerge from darkness to steal the lives of those who become lost in mountains.
Pokemon LeafGreen: On the night of the full moon, if shadows move on their own and laugh, it must be Gengar’s doing.
Pokemon Diamond: It hides in shadows. It is said that if Gengar is hiding, it cools the area by nearly 10 degrees F.
Pokemon Pearl: Lurking in the shadowy corners of rooms, it awaits chances to steal its prey’s life force.
Pokemon Platinum: The leer that floats in darkness belongs to a Gengar delighting in casting curses on people.
Pokemon HeartGold: It steals heat from its surroundings. If you feel a sudden chill, it is certain that a Gengar appeared.
Pokemon SoulSilver: To steal the life of its target, it slips into the prey’s shadow and silently waits for an opportunity.
Pokemon Black: The leer that floats in darkness belongs to a Gengar delighting in casting curses on people.
Pokemon White: The leer that floats in darkness belongs to a Gengar delighting in casting curses on people.
Pokemon Black 2: The leer that floats in darkness belongs to a Gengar delighting in casting curses on people.
pokemon White 2: The leer that floats in darkness belongs to a Gengar delighting in casting curses on people.
Pokemon X: It hides in shadows. It is said that if Gengar is hiding, it cools the area by nearly 10 degrees Fahrenheit.
Pokemon Y: Hiding in people’s shadows at night, it absorbs their heat. The chill it causes makes the victims shake.
Pokemon Omega Ruby: Sometimes, on a dark night, your shadow thrown by a streetlight will suddenly and startlingly overtake you. It is actually a Gengar running past you, pretending to be your shadow.
Pokemon Alpha Sapphire: Sometimes, on a dark night, your shadow thrown by a streetlight will suddenly and startlingly overtake you. It is actually a Gengar running past you, pretending to be your shadow.
Pokemon SUN: Should you feel yourself attacked by a sudden chill, it is evidence of an approaching Gengar. There is no escaping it. Give up.
Pokemon MOON: It apparently wishes for a traveling companion. Since it was once human itself, it tries to create one by taking the lives of other humans.
