Pikachu is a short, chubby, rodent-like Pokémon with yellow fur all over its body. Pikachu's ears are long and come to a point with black tips. It has a small mouth, which resembles a sideways 3, it has black eyes and two red circles on its cheeks. Its forearms are short and somewhat stubby, with 5 digits on each "hand" and its feet have three digits. It has two brown stripes on its back, and its tail is in the shape of Zigzag-styled lightning bolt, with a patch of brown fur at the base of the tail. Although it is technically a quadruped, on multiple occasions it has been shown to be able to stand and walk upright on its hind legs.
A female Pikachu has a v-shaped "dent" at the end of its tail. Male Pikachu do not have this dent. In Black and White, male Pikachu have less black covering their ear, though this is only shown in frontal sprites.
Exclusive to Pikachu is the ability to release electric discharges of varying intensity, at will, through electric sacs in its cheeks. This electric energy can be manipulated into a variety of techniques which are mostly used in battle, but which can be used to roast Berries as well.
As Pikachu builds up energy in its electricity glands, it often needs to discharge, as to not result in a short, or worse, which can lead to physical paralysis, or in severe cases, death. Pikachu release the built-up energy through their tail, which acts as a grounding rod, to remove unneeded energy safely. A sure sign that a location is inhabited by Pikachu is to look for patches of burnt grass, which is the result of the discharge. Through an inability to release a buildup of electricity, a Pikachu may develop a rare condition similar to the human flu. This illness is most often caused by strong nearby electromagnetic forces, which severely affect the electric glands. If a Pikachu is introduced to a magnet, it will be attracted towards its cheeks and display other common attributes of magnetism.
Pikachu is known to have acute senses of hearing, thanks to its large ears. Most domestic Pikachu are able to understand and interpret human speech at levels far surpassing those of any pet dog.
In the wild, Pikachu often travel in packs, and are rarely territorial. However, when threatened, a group can generate an intense electrical offensive, and the electromagnetic forces exerted by the resulting field can even produce a short lived, localized thunderstorm. Pikachu can be harmful pests, eating and sometimes destroying telephone poles, wires, and other electronic equipment.
Despite this, it is a popular pet, and relatively easy to maintain, with little exercise necessary for its well-being. However, it is important to discharge the electricity in its cheeks periodically.
As many know, pulling on a Pikachu's tail will result in a severe shock to the offender. Another defense of Pikachu's is the use of its nasty bite, which has been known to leave quite a mark.
They are found mostly in forests, but possibly because of their attraction to electricity or simply because they are not afraid of people, Pikachu commonly show up in civilized areas. They may even enter houses, presumably attracted by the electrical output generated by the dwellers' appliances. Pikachu are native only to the Kanto region (specifically, Viridian Forest and the Kanto Power Plant).
Living in forested areas, Pikachu often are found foraging for Berries. Instead of climbing trees, they use small electrical shocks to release the Berries from the tree, roasting them at the same time.
As pets, they can be fed a variety of processed food. Alternatively, like most Pokémon, Pikachu are tolerant to most "human" foods, and sometimes enjoy them more than the more nutritional food designed for their biology.
This Pokémon was unavailable prior to Generation I.