It is not known to evolve into or from any other Pokémon.
Along with Entei and Suicune, it is one of the legendary beasts created by Ho-Oh after the burning of the Brass Tower. Of the three legendary beasts, Raikou is said to represent the lightning strike which ignited the fire that consumed the Brass Tower.
Raikou is a yellow tiger-like creature with black stripes that resemble lightning bolts and a white under-side. Raikou has a skinny, light-blue tail with an electric spark-shaped formation at the end. Raikou appears to have a grayish-purple cape that is supposedly made of thunderclouds. Most of Raikou's face is white with a light-blue "X" on its face and a gray crest on its forehead. Raikou has red eyes and long fangs in its upper jaws that make its appearance similar to the sabre-tooth cat.
Raikou is a genderless species.
Raikou has the ability to shoot bolts of lightning from the rain clouds on its back. Raikou can also attack using its fangs and has limited psychic powers. Raikou has the ability to create storm clouds from its cape, allowing it to fly.
Raikou is normally distrustful of humans due to the fact that humans have tried to capture the Legendary Beast of Thunder for many centuries, though it has shown some friendship with those that just wish to help it. Raikou tends to show up either when there is a thunderstorm or when other Electric-type Pokémon are in danger.
As a member of the legendary beast trio, Raikou is constantly on the move and seems to lack any set place where they show up.
Raikou's large fangs suggest that it is a carnivore.
This Pokémon was unavailable prior to Generation I.