It has the Pressure ability which decreases the target's PP if they use that move on Raikou. It can also have Volt Absorb as its other ability if obtained from the Dream World.
Raikou is a tiger-like creature. It carries rainclouds on its back which let it fire Thunderbolts at will. It descends with the lightning, and races across the land barking a cry that shakes the ground and sounds like crashing thunder. While running it stores up static electricity, then shoots off the excess. It is also said to help other electric Pokémon if they are in danger.
In the anime
Raikou appears in the episode The Legend of Thunder!, where it's captured by Team Rocket and then saved by Jimmy and his Typhlosion.