It is not known to evolve into or from any other Pokémon.
Along with Raikou and Entei, it is one of the legendary beasts created by Ho-Oh after the burning of the Brass Tower. Of the three legendary beasts, Suicune is said to represent the rains that quenched the flames of the burning Brass Tower.
Suicune is the version mascot of Pokémon Crystal, appearing on the boxart.
This section temporarily contains information copied directly from Bulbapedia, and needs to be rewritten so not to be classified as plagiarism.
Suicune is a slim, quadruped, blue, mammalian Pokémon with white, diamond-shaped spots. Its face and underside are white as well. Suicune has a thick, purple mane that resembles the aurora borealis and two white, streamer-like tails that wave forward. It has a long, white snout. Suicune has a large, hexagonal, cerulean blue crest on its forehead that resembles the antlers of a Qilin with two prongs on either side of the base. It has red eyes, a protrusion under its chin, and small paws with white paw pads.
Suicune has the power to walk across water and purify dirty water with one touch. It travels across grasslands in search of water to purify. Northern winds always seem to blow stronger in its presence. In Pokémon Crystal, Suicune is said to be the closest of the legendary beasts to Ho-Oh. It is also said to have a link to the Unown. In the anime, Suicune is shown to be heroic, serious, and calm during dangerous situations.