Pokedex Entry #94:

Gengar, the Shadow Pokemon. It hides in shadows. 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. It is said that if GENGAR is hiding, it cools the area by nearly 10 degrees F. The leer that floats in darkness belongs to a GENGAR delighting in casting curses on people. 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. To steal the life of its target, it slips into the prey's shadow and silently waits for an opportunity.

Now you can make Gengar your companion with this large Gengar plush!