Taken from the PCKJ version of the Colosseum Bonus Disc. One of the two ways Celebi is acquired in Generation III for Japanese Region. It's LV10 and know it's common moves. I've posted this on a couple of other Forums, but haven't had much time to make a post on the blog for these. I was meaning to do Colosseum Pikachu, which is also common with it's moves. I'll have to get to that at some point too.
Celebi though requires a cleared Colosseum Save, and can be transferred up to 48 Japanese GBA Cartridges, once per Save File. I've also done the Pal Park and Shifter transfers incase players of the newer Generations didn't have access to older hardware. If you wanted to use my Emerald Save to do this yourself. You'll need a Retail Cartridge of Emerald, and a way to upload the save file to Cartridge. Save should also be Region Free.