Gengar

Gengar is a dark purple, bipedal Pokémon with a roundish body. It has red eyes, a wide mouth that is usually curled into a sinister grin, and pointed ears. On its back are numerous spikes, and it has smaller spikes on top of its head similar to tufty fur. Its arms and legs are short with three digits on both its hands and feet. It also has a stubby tail.

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. It is shown in Pokémon the Series that Gengar can fly, turn intangible, possess people and other Pokémon, create illusions and extend its tongue by several meters.

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's shadowy powers can also be manifested offensively. Being the result of an Evolution via trading, Gengar is rarely found in the wild, though they can be found in 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. As mentioned in Pokémon Sleep, Gengar is known to sleep deeply while hiding in the shadow of a target it plans to curse.

Forms

Gengar has two forms: Mega Gengar and Gigantamax Gengar.

Mega Gengar

As Mega Gengar, a portion of its body sinks into the ground, and its arms and tail lengthen. 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. The spikes on Mega Gengar's back are more numerous and pointed, and additional spikes appear on its hands and tail. Its ears are now considerably longer and tilt backward.

Mega Gengar has the ability to access other dimensions and has a vicious nature. Mega Gengar has no interest in opponents unless perceived as prey. Its relationships are warped due to Mega Evolution. It now desires to take and curse the life of anyone or anything in its path; it may even curse its own Trainer. Mega Gengar sinks into another dimension to wait for a chance to attack.