from pre pokemon colosseum is where you get jirachi
from nintendo event

moon

GET a full 200 pokedex, beat every event at battle tower, and beat the Elite Four.
You will get three stars by your trainer card name.

by going to stollpolis city and go in cave.

Get a full pokedex of 200 pokemon beat every event at battle tower and the elite four you will have four stars.go to mossdeep island's space center talk to the man whom is about to launch the space shuttle he will let you on.after in space you will land on the moon.when you come out you will be in a suite.explore until you get into a battle with legendary pokemon like Groudon Kygore Raquaza Mewtwo Mew Jarachi
Lugia Ho-OH even some from oter games like Zapdos Moltres Articuno and Latias Latios. The last battle you encounter will be a Deoxys

if you go to the cave of Origin you will find Groudon or Kygore

Deoxys you can get by mixing records with an emerald which has the ticket to go to birth island (by cheating or an event) or trading it, but there IS NO MOON!!!
Jirachi you can trade with the pre-order disc of pokemon colluseum, or get a wish tag (get about 5 pokemon with pick-up and look in the seafloor cavern)and go to the white rock, it cracks open and out comes jirachi.

Deoxys you can get by mixing records with an emerald which has the ticket to go to birth island (by cheating or an event) or trading it, but there IS NO MOON!!!
Jirachi you can trade with the pre-order disc of pokemon colluseum, or get a wish tag (get about 5 pokemon with pick-up and look in the seafloor cavern)and go to the white rock, it cracks open and out comes jirachi.

you must have a wish tag