Raikou ( ライコウRaikō?), known as the Thunder Pokémon, is one of the three "Legendary Beasts" that are featured in Pokémon Gold, Silver, and Crystal. According to legend, the Legendary Beasts were reincarnated by Ho-Oh from the spirits of three Pokémon which died in the fire that gave Burnt Tower its name. They are awakened in this tower in their first appearance. Another myth maintains that Raikou descended to earth together with a lightning bolt. Each Beast personifies a force of nature - Raikou, in particular, embodies the speed of lightning.
Raikou is a yellow tiger-like creature that stores tremendous energy inside its body. It has black stripes that resemble lightning bolts and a white under-side, and a skinny, light-blue tail with a star-shaped formation at the end. Raikou appears to have a 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. It has the ability to shoot bolts of lightning from the rain clouds on its back. Raikou's roar is aptly described as "thunderous". It is loud enough to create shock waves and shake the ground as if actual thunder had struck. Raikou is normally distrustful of humans because 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. As a member of the legendary beast trio, Raikou is constantly on the move, although it tends to show up either when there is a thunderstorm or when other Electric-type Pokémon are in danger.
Raikou first appears in the Game Boy Color video games Pokémon Gold and Silver. Upon being approached by the player's character, Raikou, along with its counterparts Entei andSuicune, flee, traveling at incredible speeds across Johto. The three of them will randomly appear on a certain route, fleeing from battle at the first opportunity. The three of them later appear in Pokémon FireRed and LeafGreen; however, only one of them appears in a single play through. If the player chooses Squirtle, Raikou will appear in a similar fashion to how it appeared in Gold and Silver. In Pokémon HeartGold and SoulSilver, Raikou is encountered similarly to how it is in Gold and Silver. To promote the release of Pokémon Black andWhite, players can download the shiny Entei, Raikou, and Suicune from GameStop stores on various weeks in January and February 2011, which will activate the Zoroark event in the games. Raikou also appears in the Gamecube game Super Smash Bros. Melee, when released from a Poké Ball, Raikou releases a powerful Spark attack that electrocutes any opponents that get caught in it.