Jirachi

Jirachi is super-rare legendary Pokémon that first appeared in Pokémon Ruby and Sapphire. Jirachi is a transliterated version of the word "to wish" in Russian, which is something like "jhelat".

According to the Pokédex, Jirachi is a wish-granting Pokémon, who, when it awakes, will grant any wish written on the three paper-like things on its head. Writing your wish might be hard though, as it can defend itself even while sleeping. The only way to awaken it is to sing to it with "a voice of purity", and even then it's only awake for seven days every thousand years. Jirachi is based on the Japanese Tanabata, a star festival held on July 7. On Tanabata, it is customary to write wishes on slips of paper (similar to the things hanging from Jirachi's head) and hang them on bamboo.

Of note is Jirachi's signature move Doom Desire. A Steel-type move, it has an attack power of 120 and hits two turns after use, making it similar to the Psychic move 'Future Sight' -- except much more powerful. All of Jirachi's base stats are at 100 as well, similar to Mew, making it considerably powerful.

Availability
Jirachi cannot be caught in the wild in any game. It is a promotional Pokémon similar to Mew and Celebi of the first and second generation games. However, Jirachi has been offered in some promotions—there is a 1 in 1000 chance of downloading it from the Pokémon Center machines in the Pokémon Centers of Osaka, Japan and New York City. A bonus disc containing Jirachi was also given out for those who pre-ordered Pokémon Coliseum before February 9, 2004.