Now I know that Celebi is an event Pokémon in the Gen II games, but is there a way to obtain this Pokémon without the use of a cheating device?

Not a clue.

A Japanese copy of crystal can get one legit, but nothing else can. Plus, you can't trade between a Japanese version and an English version (times have changed).

I found this video a long time ago.

Hey, Thanks for the video, I'll try it as soon as blow the dust off on my n64.

You gan also glitch a Teru-sama. Ways include turning off the N64 while saving Item Box data on Stadium 2. I believe bad clones also sometimes hold Teru-samas. There are 29 different places in hexadecimal, most of which act as GS balls. Take one to an AIDE in Professor Elm's lab, take it back the next day, and take it to the shrine in Ilex Forest. You will then encounter a Celebi.

I'll stick with the Youtube video, but i am still trying to find my pokemon stadium 2, goes to shed.