Pokemon Bad Egg: What It Is and How to Fix It

One of the most frustrating things a Trainer can encounter while playing their favorite Pokemon game on the GBA or NDS is discovering that a Pokemon they just caught has suddenly turned into a Bad Egg.

Bad Eggs in the mainline Pokemon games have been existing for quite some time now, specifically originating from Generation 3. 

Despite its name, it isn’t actually a Pokemon Egg but rather an error handler or a way for the games to show that the data for that Pokemon has been either corrupted or incorrectly altered.

While it might look like harmless stuff that takes up space in your party or PC, a Bad Egg is notorious for messing up the player’s saved data.

To know more about Bad Eggs, this post will provide you with all the information you need, including the most important ones — fixing them across various Pokemon games.

What Is a Bad Egg?

A Bad Egg is an error handler caused by a checksum mismatch. It is basically garbage Pokemon data shown in the form of a Pokemon Egg. It has no use in battle, and if ever it hatches, it often just turns into another Bad Egg or worse, freezing your game or corrupting your save file.

The worst case about a Bad Egg is that you can’t get rid of it once it is on your PC using the game’s default options. The Release option doesn’t work on Bad Eggs.

Why the Game Shows One

If a Pokemon game produced a Bad Egg, it means that specific data about a Pokemon doesn’t match with the checksum that is saved in its system. Every time you play a Pokemon game, a series of processes runs in the background, and some of them are designed as a security measure to check whether a Pokemon’s data has been altered or corrupted.

So, once newly loaded Pokemon data fails a checksum test, the tendency of the game is to turn that Pokemon into a Bad Egg.

What a Bad Egg Can and Can’t Do

Here are some of the things that the Bad Egg does to a game:

• Occupies a PC storage space permanently. If you will just rely on the in-game features, there’s no way you can release or delete a Bad Egg. It will be forever stored in your PC.
• Freezes or crashes your game. Sometimes, viewing the summary or the details of the Bad Egg can make your game suddenly pause or crash.
• Corrupt your save file. Further interaction with a Bad Egg can cause your save file to become unusable the next time you boot your game.

On the other hand, a Bad Egg can’t do several things, such as:

• Hatching a normal Pokemon. Forcing a Bad Egg to hatch may lead to further problems, particularly the freezing and crashing of your game.
• Releasing it back into the wild. As already mentioned, you can’t get rid of it by normal means.
• Trading it to another player. Even if you’re playing on an emulator, which sometimes allows you to trade with yourself, you can’t select a Bad Egg for trading.
• Battling Pokemon. It’s just data that the game itself can’t make sense of, so it’s not considered a Pokemon or even an item.

What Causes a Pokemon Bad Egg?

This section will reveal all possible sources of the Bad Egg in Pokemon games, spanning those that are released for the GBA and NDS.

Cheat Codes (The Usual Cause)

Since cheat codes edit the game’s memory directly, they might mess up saved data in the game. Because cheat codes usually don’t recalculate the checksum, the new information they provide doesn’t match it, and the game recognizes the changed data as a Bad Egg.

Of course, this doesn’t mean that cheat codes in general cause Bad Eggs. If you use a cheat code correctly and follow any additional instructions, the game should continue to work normally while the cheat is active.

Also read: How to Fix Not Working and Glitchy Cheats for Pokemon GBA Games

Using Cheat Codes From a Different Pokemon Game

For those who have experience using cheat codes in classic Pokemon games, it’s a no-brainer that using a FireRed cheat on Pokemon Platinum won’t just cause the cheat to fail. It can also result in glitches, corrupted data, or other unexpected issues.

If you use the wrong cheat code for a specific Pokemon game or version, the chances of the game producing a Bad Egg can increase significantly. Make sure you only use cheat codes specifically designed for your game and version.

Running Too Many Cheats at Once

Even if you use a cheat correctly and it doesn’t immediately cause a Bad Egg, activating another cheat or several cheats at once can still cause one to appear. This is because multiple cheats can sometimes overlap their effects on the game’s memory, with one code writing over an address that another code is also trying to use or that a Pokemon’s data currently occupies, leading to corrupted or inconsistent data that no longer matches its checksum.

Non-Cheat Causes — the Pomeg Berry and Mail Glitches

Bad Eggs aren’t exclusive to cheating. In Pokemon Emerald, the Pomeg Berry glitch exploits an oversight in how the berry lowers a Pokemon’s HP, pushing certain data into a state the game was never designed to store or read correctly. Because this happens through legitimate in-game items, no cheating device is involved, yet the resulting data still fails the checksum check, so the game flags it as a Bad Egg.

The Mail glitch works the same way but in a bit different way. In Pokemon Ruby, Sapphire, Emerald, FireRed, and LeafGreen, an unintended interaction with removing Mail from a Pokemon can corrupt the data it reads or writes to. Since this bypasses the game’s normal checksum recalculation, any Pokemon whose data is altered this way ends up with a mismatched checksum and turns into a Bad Egg. 

In other words, both of these known glitches prove that a Bad Egg doesn’t discriminate based on whether cheats were used. As long as a piece of data doesn’t match the game’s stored checksum value, it becomes a Bad Egg, even if it happened through legitimate game cartridges.

How to Get Rid of a Pokemon Bad Egg

Now that you know what a Bad Egg is, it’s time for you to learn the most common ways to take it off your game before it causes any problems.

If You Haven’t Saved Yet

If your last save was made before you encountered the Bad Egg, you don’t have to do anything other than restart the game. Once you load your previous save, the Bad Egg should no longer be there. 

Although this will erase any significant unsaved progress, such as encountering a rare Pokemon, at least your last save file should remain safe from potential corruption.

Reloading an Earlier Save

We at PokeCoders always encourage our readers to keep a backup save file when playing a Pokemon game, regardless of the version or whether it’s from the mainline series or a ROM hack.

Having a backup save file can be especially useful in situations like this. If a Bad Egg appears, you can simply replace the affected save file with a backup that doesn’t contain it and restart the game.

Using PKHeX

PKHeX is a popular tool for editing the save files from all Pokemon games, from Generation 1 to Generation 9. It can do a lot of things with your saved progress, such as adding rare Pokemon, changing their gender, and even deleting them.

You can easily remove Bad Eggs using PKHeX by opening your save file and accessing the Pokemon storage. From there, you can either mark the Bad Egg’s slot as empty or use the tool’s delete option, just as you would with a normal Pokemon.

If you’ve never used PKHeX before, you’re missing a lot of features that cheat codes sometimes can’t replicate. Check out our complete beginner’s guide if you want to try this method for removing a Bad Egg.

Triggering the Emerald Battle Tower Cloning Glitch

This method, as the name suggests, only works if you’re playing Pokemon Emerald. This is because Pokemon Emerald features the Battle Tower, a location from the game’s Battle Frontier content.

1. You can start the glitch at the Battle Tower by going inside and depositing any Pokemon in your party that you want to make a copy of. 
2. Save the game, withdraw all the deposited Pokemon, and go to one of the attendants who handle the options for the Link Multi Battle Rooms.
3. After selecting the two required Pokemon and reaching the save options screen (where you can choose Yes or No to save), restart the game instead of saving.
4. Load your previous save, and you should now have copies of the Pokemon you deposited earlier: the original versions in your party and their copies in your PC.

Depositing a Bad Egg instead of a Pokemon using this method will delete the Bad Egg from your PC.

What Doesn’t Work (And Why)

While the abovementioned methods are often enough to remove Bad Eggs in Pokemon games, several practices that new players might try are known to fail in fixing the issue. These are:

• Depositing a Bad Egg in a PC. Putting a Bad Egg in your PC will free up a space in your party, but it won’t solve the problem. Based on our in-game tests in a GBA ROM hack called Pokemon SoulGold, a Bad Egg will remain in your storage and can continue to pose a risk to your save file.
• Releasing a Bad Egg. This is one of the main reasons players get frustrated with Bad Eggs, as the game generally prevents them from being released. Trying to release one won’t fix the issue.
• Trading a Bad Egg. Some Pokemon games don’t allow Bad Eggs to be traded, making this another dead end when trying to get rid of one.

Bad Eggs on GBA Games

This section covers the behavior of Bad Eggs across several GBA entries of the Pokemon franchise.

FireRed and LeafGreen

In Pokemon FireRed and LeafGreen, Bad Eggs are created when the game detects invalid Pokemon data, which can happen because of corruption, glitches, or improperly modified data. Once a Pokemon becomes a Bad Egg, it cannot battle, hatch, or be released like a normal Pokemon.

Emerald, Ruby, and Sapphire

Pokemon Ruby, Sapphire, and Emerald also use Bad Eggs to handle invalid Pokemon data. In Ruby and Sapphire, however, there is a weird and interesting thing that can happen to Bad Eggs — they can still hatch.

As you walk, the Bad Egg will keep on counting your steps, and once it reaches the required number of steps for it to hatch, it will trigger a softlock before it even reveals the Pokemon that hatches from it.

Why ROM Hacks Behave Differently

ROM hacks can change the original game’s code and Pokemon data, meaning their Bad Egg behavior may differ from the official GBA games. 

ROM hacks made with decompiled FireRed and CFRU (Complete FireRed Upgrade) use a Pokemon data system that decrypts existing data, eliminating the checksum check that can trigger Bad Eggs. This is why FireRed-based hacks like Pokemon Radical Red generally don’t have problems with Bad Eggs, while some Pokemon Emerald hacks still can.

Bad Eggs on DS Games

Bad Eggs continue to appear in the NDS era. While their basic purpose remains the same, some games have their own quirks in how they display or handle them.

Platinum, Diamond, and Pearl

In Pokemon Diamond, Pearl, and Platinum, Bad Eggs are treated much like regular Eggs. They cannot battle, hatch, or be released, and having one in your party can also prevent you from accessing certain multiplayer features.

HeartGold and SoulSilver

Pokemon HeartGold and SoulSilver follow the same general behavior as the other Generation IV games. A Bad Egg cannot normally be battled, hatched, released, or traded, which means it can remain stuck in your party or PC unless you use another method to remove it.

Black, White, Black 2, and White 2

Generation 5 games have an interesting naming difference when it comes to Bad Eggs. Pokemon Black and White display a Bad Egg simply as “Egg,” while Black 2 and White 2 use the more familiar “Bad Egg” name. Other than the names, they work quite similarly to conventional Bad Eggs from other games.

How to Avoid Bad Eggs in the First Place

The best way to avoid Bad Eggs is to use cheat codes specifically made for your Pokemon game and version. Avoid mixing codes from different games or activating multiple cheats that modify the same Pokemon data.

Most importantly, always keep a backup of your save file before experimenting with cheats. If something goes wrong and a Bad Egg appears, you can simply restore your clean save instead of risking your main progress.

Frequently Asked Questions

Final Thoughts

Bad Eggs are quite tricky to remove, especially for those who aren’t familiar with how Pokemon games process data. But with all the fixes that we discussed, you should be able to try one of them and see if it saved your progress from possible corruption.

The best way to protect yourself from a Bad Egg is to keep a backup of your game’s save file. Once you locate the folder containing your save, simply copy the file and create a separate backup folder where you can store it for easy access if something goes wrong.

Keep up with the best cheats, fixes, and recommendations for Pokemon ROM hacks and emulators! Stay tuned to PokeCoders for more updates and everything happening in the Pokemon ROM hacking community.