From Bulbapedia, the community-driven Pokémon encyclopedia.
The Celebi egg trick is a method to obtain Celebi in the Generation II games. Due to the fact that it is impossible to obtain Celebi via standard gameplay, this is, currently, the only way to get Celebi in the Generation II games without a Nintendo event. However, like most other glitches, it may damage the player's save data.
This glitch was first documented at Glitch City Laboratories. 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.
This is only one known method of carrying out the Celebi egg trick and successfully obtaining the Celebi.
- The egg - The player must get an egg that will know Beat Up as its third move upon hatching. This can be done 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. Because both parents have the same moveset, the offspring will share this moveset.
- The bad clone - The player must get a bad clone, a clone with a name made of only question marks and will be level 0. This can be done by Pokémon cloning. The box that is used for cloning must not 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. The chance of getting a bad clone is at maximum if the box has 15 to 18 Pokémon.
- Last requirement - The player must get any five Pokémon (preferably weak, common or otherwise useless Pokémon). They only have to know four moves each. The easiest way to get them is to clone a Pokémon knowing four moves until there is a bad clone. Because getting a Bad Clone takes some tries, he or she will get five unimportant Pokémon knowing four moves each as a positive side effect of the bad clone action.
- Step 1 - The player must first deposit the egg into a box. The five other Pokémon and the bad clone have to be in the party.
- Step 2 - The player must then go to the daycare and ask the man to raise the bad clone. He or she should then take it back from him, and it will be a ?????.
- Step 3 - Next, the player must put ????? at the top of his or her party and go to the PC.
- Step 4 - Using the "Move Pokémon without mail" option, the player must move any Pokémon (preferably weak or common Pokémon) from a PC box to the top of their party. Its name should become the name of its original Trainer. The player will now have 7 Pokémon in his or her party.
- Step 5 - Next, the player must go back to the Daycare man and ask him to raise the ?????. Afterward, he or she should return to the PC.
- Step 6 - Back at the PC, the player must deposit the first and second party Pokémon.
- Step 7 - Using the "Move Pokémon without mail" option, the player must move the egg from its PC box to the top of his or her party.
- Step 8 - Next, the player needs to deposit the next four party Pokémon, but not the egg.
- Step 9 - Subsequently, the player should withdraw any Pokémon that he or she didn't use for the trick.
- Step 10 - Having completed the set up, the player should walk or bike around until the egg hatches into a Celebi. However, the Celebi is still unplayable.
- Step 11- The Celebi will hatch at level 0. Due to how the game handles Pokémon that level up in battle, the player must allow the daycare couple to raise the Celebi to at least level 2. After this, it works like any normal Celebi.
The reason why the player gets Celebi is the Beat Up move. In Generation II, both Celebi and Beat Up share the same index number: 251. This is not random, and should work with any other move-Pokémon combination; Psychic, whose index number is 94, should result in a Gengar hatching, while Splash, despite being the worst move, ironically would bring about a Mewtwo, as both share index number 150. This glitch therefore should not cause any glitch Pokémon to appear, as there were exactly 251 moves in Generation II, though Ledyba would not be obtainable in this way, as Struggle is unobtainable normally as a move.
If the Pokémon used for the breeding have no third attack, the Pokémon that will come out from the egg (after the glitch) will be the Glitch Pokémon #000 ?????.
This Pokémon cannot be deposited or released in the player's PC since it cannot be seen by the PC.
If a wild Ditto is transformed into that hatched ?????, the wild Ditto is no longer catchable by any kind of Poke Ball. Even a Master Ball will fail to capture it.
????? can also be found just by breeding a "bad clone" with a Ditto and the only move it will know is Transform.
The fourth move
The hatched Pokémon will hold an item depending to the fourth attack of the Pokemon used for the breeding. Both the item and the fourth attack share the same index number. For example, if the two Pokémon (used for the breeding) have as fourth attack the move Reflect, the hatched Pokemon will hold a GS Ball. That's because both GS Ball and Reflect have the same index number: 115.