Celebi Egg glitch
The Celebi Egg Trick is a confirmed method to obtain Celebi in the Pokémon Generation II games. Due to the facts that it is impossible to obtain Celebi via standard gameplay, this is, up to now, the only way to get a Celebi with the stat of a Pokémon caught in the game itself (OT and ID number) without using any cheating devices. However, using this glitch might damage your save data.
Requirements
Below is what you need to do this glitch.
The Egg
Get an Egg that will become a Pokémon knowing Beat Up as its third move. You can do this by training a male and a female Sneasel up to Level 57. Both Sneasel need to have the same four moves in the same order, with Beat Up at position three. The new Pokémon obtained by breeding will have the identical move scheme, this is because the parents have an identical move scheme. Note: The Pokémon shall hatch from the Egg during one of the last steps of the glitch!!!
The Bad Clone
Get a Bad Clone. This can be done by Pokémon cloning. The box that you use for cloning mustn't be totally filled up at any time (otherwise the box is unable to produce Bad Clones). Getting a Bad Clone is a case of luck and occurs sometimes during the act of cloning. A Bad Clone will have Level 0 and the name is filled with "?"! Note: If the box has a content of 15 to 18 Pokémon, the chance of getting a Bad Clone is at maximum!!!
Last Requirement
Get any five Pokémon you don't care too much about. They only have to know four moves each. The easiest way to get them is to clone a Pokémon knowing four moves until you get a Bad Clone. Because getting a Bad Clone takes some tries, you will get five non-important Pokémon knowing four moves each as a positive side effect of the Bad Clone action.
How to do the glitch
Step 1
Deposit the Egg into a box. The five other Pokémon and the Bad Clone have to be in your party.
Step 2
Go to the Daycare and talk to the man. Ask him to raise the Bad Clone. Then take it back from him, and it will be a # 000.
Step 3
Put # 000 at the top of your party and go to the PC.
Step 4
Using the "Move PKMN w/o mail" option, move any Pokémon you don't care about from a PC box to the top of your party. Its name should become the name of its original trainer (OT). You will now have 7 Pokémon in your party.
Step 5
Go back to the Daycare man and ask him to raise your # 000, then go back to the PC.
Step 6
Deposit the first and second party Pokémon.
Step 7
Using the "Move PKMN w/o mail" option, move the Egg from its PC box to the top of your party.
Step 8
Deposit the 4 next party Pokémon (not the Egg).
Step 9
Withdraw any Pokémon that you didn't use for the trick.
Step 10
Walk around a few minutes and the Egg should hatch.
Step 11
Go to the Daycare man and let him (her) raise your Celebi from level 0 to level 1. Then repeat this to let him (her) raise your Celebi up to level 2. Now your Celebi works as a normal obtained Pokémon. Note: If you level up a Pokémon below level 2 via battle, the Pokémon will ultimately grow to level 100.
Further Possibilities
The reason why you get Celebi is the Beat Up move. Have a look at the List of moves in other languages and you will notice, that Beat Up has the same number as Celebi: 251. This is not random. Referring to the Celebi Trick (mentioned in Sources), the Pokémon you get depends on the move. One example: Get an Egg that will become a Pokémon knowing Splash as its third move (a couple of Gyarados instead of Sneasel) and do the Celebi Egg Trick. The the result of it should be a Mewtwo, as Splash has the number 150, as well as Mewtwo. But this possibilities have still to be confirmed.
Sources
This Glitch has been taken from GlitchCityLaboratories. It was found by Paco81. There is another way to get Celebi, called Celebi Trick (also found by Paco81), but these two glitches are slightly different. Just to avoid confusion.
