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Guide to Getting Started Modding Ultimate

A Tutorial for Super Smash Bros. Ultimate

1. Introduction

This tutorial will be guiding you through from scratch on how to begin modding Super Smash Bros. Ultimate.

1.1. Before Getting Started

NOTICE: For the below, creating an emuMMC is not required and is generally not necessary for only modding this game. However, other CFW usage may vary. Please read the guide and stop at the emuMMC step. If you would like to create one anyway (or stay as safe as possible), you may do so as you please.

If you are new to Switch hacking, please read up on this guide which will guide you from stock to CFW. Be sure to read the FAQ to answer some questions you may have regarding Switch hacking!

This guide will always contain the most up-to-date information on preparing to mod Ultimate.

A micro SD card formatted to FAT32 is highly recommended to avoid file corruption. If you are unable to format your card to FAT32 (please also follow the fourth entry in the Q&A section to get the best load times):
  • Use guiformat if you're on Windows
  • Use GParted if you're on Linux
  • Use Disk Utility if you're on macOS (Select "MS-DOS (FAT)", even if the card is larger than 32 GB)

Having issues with the guide? Please consult me in the comments or join the Smash Ultimate Modding Hub Discord server and ask in the help channels.

IMPORTANT: Please do not make video tutorials from this guide unless permission is given. Your video tutorial will eventually contain outdated information since this tutorial is updated frequently with new information and it is very difficult to help users who have followed video guides. Please be respectful of my and the community's wishes.
Please do not redistribute this guide's text onto other websites or platforms. Instead, link the guide. If you would like to translate this guide for another language, please contact me and I can figure out a way to include it here.


I assume no responsibility for any kind of ban or brick by following this guide. You take the risk by running the unsigned software. If you follow the instructions exactly as written, you will be fine.

2. Requirements

  • A micro SD card with at least 16 GB of free space
  • Ultimate Mod Manager (Download Ultimate_Mod_Manager.nro and place it inside of the switch folder)

3. Game Dumping

A game dump is required because we have to inject our modified data into the game's data.arc file, which is the game's entire file container. In the future, it may be a basic drag and drop system like most games are when modding.

1. Reinsert your micro SD card into your Switch and boot into CFW
2. Go into the home menu, hold R and launch Smash. Continue to hold it until the Homebrew Menu appears
3. Navigate to Ultimate Mod Manager and launch it. You will be automatically taken to the dumper
4. Depending on what format your micro SD card is formatted to, press either A or Y. This process may take a while

(Optional) NOTICE: While the below is an effective way of ensuring a good dump, launching the game is much quicker. If you would just like to make sure, you may follow the optional step.

Once complete, hold R and press X to generate an MD5 checksum of the dump. This is to check to ensure that the dump is a good dump. Verify that the outputted hash matches whichever game version you have installed here:
1.0.0 = 15A788783C82E6563D54F75D6E2C3A3F
1.1.0 = EB8BEB3ED8D84A6BD648C3F1AE560EB3
1.2.0 = 15FF393BE3658BF4EDBB51E53A7B331D
1.2.1 = 5FE3469414DC7DB0A4788E0115DD082F
2.0.0 = 4454CCFBAFAEAF6CB6B7F3446CD38250
2.0.1 = B5B4B955001D2192006CEC6542F221A7
2.0.2 = D594F5E5986C2191B68932310BA22226
3.0.0 = 1DF935124525AF928278EDDF518A2F9C
3.0.1 = 0B483FD9870464B770668DCD9B9AE0BD
3.1.0 = 0472A56A03C1800C4EFD12CA7D3F3E8D
4.0.0 = EC434E0280A7BC28B73A1361F5930CD6
5.0.0 = 49A4E00CDD127971BD12B555E946EAC6
6.0.0 = 2A419E68A943ED4C13D73375284F641E
6.1.0 = B362AA3C9B9ED3C45C2D3BF7ED7D7966
6.1.1 = F758FB0E552C1360A7AE059A661B29E4
7.0.0 = A27496A6F7A01F9E77E4019E4307E785
If the outputted hash matches, you may exit the application and shut down your Switch.

3.1. Troubleshooting: Hash does not match my game version in list!

If this issue is occurring, you may have installed NSPs for either the base game, update, or both. If this is the case, everything should still work fine, but I encourage you to download the titles legitimately to lower the amount of possible issues.
There is an unknown cause and explanation as to why some users get bad dumps despite having legitimate copies of the game and updates, however a temporary switch of micro SD cards for dumpin seems to partly resolve the problem.

4. Installing Mods

4.1. data.arc Mods

4.1.1. Compressed vs. Decompressed Mods

There are two forms of mods, compressed and decompressed. Compressed mods are compressed with a lossless data compression algorithm called zstandard, or zstd, which makes files smaller. These are more often than not named by an offset, which is an absolute or relative address for a piece of data (e.g. 0x134AE2DC8.nutexb). Offsets are always version specific, so they will not install correctly on different game versions (see step 4.1.2 if your mod is compressed).

Decompressed mods are not compressed with zstandard, are organized by arc file path and name, and come pretty much ready to install. Decompressed mods work on any game version and will not require manual updating unless the file was updated in an official game update. Parameter edits are very prone to this and may not work on different game versions.

While compressed mods can be identified by the file name being an offset, the mod data can still be compressed but organized by arc file path and name.

4.1.2. Updating Mods

NOTICE: Only follow this step if the mod you want to install is named by old offsets.

To update compressed mods, you will need a Python script called OffsetModUpdater. What this Python script does is it decompresses every compressed mod file and puts everything into a decompressed structure.

1. Download and install Python 3.X if you haven't already
2. Double-click the script. If it asks to install zstandard, install it
3. When asked for the mod folder path, drag folder you want to update into the Command Prompt/Terminal window
4. When asked for the mod version, input the version that the mods offsets were made for (e.g., 1.0.0). Usually the submission page for the mod says what version the offsets were for, so use that
5. The new mod folder will output to the current working directory, in this case, wherever you have the script. The folder inside of output is what you should keep in mind as you're going to use that in the next step

4.1.3. Adding Mods

As an example for adding mods onto the micro SD card, I'm going to use my Shiny Mewtwo mod. Even though I included both the compressed and decompressed forms, please use the decompressed form. Ultimate Mod Manager requires there to be a folder between the mods folder and the first of the arc folders (fighter, stage, ui, etc.), such as a folder named "Shiny Mewtwo (Default Eye)" or "shiny_mewtwo_defaulteye", however it can be named anything. Place this folder in the directory /UltimateModManager/mods/ on your micro SD card. You may have as many mod folders as you'd like.

Once you add a mod folder or more, reinsert your micro SD card into your Switch and boot into CFW.

4.1.4. Installing the Mods

1. Go into the home menu, hold R and launch Smash. Continue to hold it until the Homebrew Menu appears
2. Navigate to Ultimate Mod Manager and launch it. You will be automatically taken to the mod installer
3.  Select any folder with A to install it. From there you can either press B to install another folder or press X to launch Smash

4.1.5. Uninstalling Mods

If you want to uninstall a mod folder, follow the same process above, but instead press Y to uninstall that folder. If you want to uninstall multiple folders, press ZR on multiple folders to select them, then press Y to uninstall them. If you want to uninstall all mods, select the option "Restore backups and file table". If you want to delete a mod folder, hold L and R and press Y on the folder(s) of choice. This will of course uninstall the mod first, then it will delete the folder.

4.2. SaltyNX Code Mods

While data.arc modding allows us to edit the game's resources, code edits allow us to edit the game's code, allowing us to achieve greater things that data.arc modding cannot. Some code mods may not require a data.arc file, but some will.

1. Download from here (the latest release currently not supported). Extract the .zip file and drag both the atmosphere and the SaltySD folders to the root of your micro SD card. Allow the atmosphere folders to merge
2. Inside of the SaltySD folder, create a new folder named plugins, and inside of that a new folder named 01006A800016E000. This is where you're going to want to place your .elf files
3. To load these plugins in-game, simply launch the game. Holding L when launching the game will not prevent these from loading, so to either prevent them from loading or uninstall them you will need to remove the .elf files from the directory

5. Conclusion

By the end of this guide, you should be comfortable with the basic modding process for Super Smash Bros. Ultimate. If you have any questions, please let me know and I'll be sure to answer you! Alternatively, please look through the Q&A to see if something there answers your question.

5.1. Q&A

Q: I want to start making my own mods. How can I do so?
A: You will need a program called CrossArc to browse through the data.arc file. This tool is useful for extracting files and getting file paths. Before opening your data.arc file, click the Update Hashes button to update yourself to the latest list of hashes. You do not need to do this every time, only on CrossArc's first startup and sometime after a new update is available. If you'd like to keep up on the hash cracking process, see this GitHub repository.

Q: Where is the data.arc file stored on the micro SD card?
A: Atmosphère 0.10.0 or higher: atmosphere/contents/01006A800016E000/romfs/
Atmosphère 0.9.4 or lower: atmosphere/titles/01006A800016E000/romfs/

Q: How do I combine the data.arc file if I'm on FAT32?
A: NOTICE: You should only be doing this if you wish to use the data.arc file with CrossArc.

For Windows, run this Command Prompt command in the romfs folder (see location above) (do not replace %UserProfile%):
copy /b data.arc\* "%UserProfile%\Desktop\data.arc"
For either Linux or macOS, run this terminal command in the romfs folder (see location above):
cat 00 01 02 03 > ~/Desktop/data.arc
This will output the combined data.arc file to your desktop for use with CrossArc. You may move it elsewhere if you wish. This combined file does not go back on your micro SD card.

Q: Why does my game have such slow load times?
A: If you are using a micro SD card formatted to FAT32, this is most likely the reason. The solution is to format your micro SD card using a 64 KiB allocation unit size (equal to 65536 bytes) while keeping the format on FAT32.
Another problem could be you're using a micro SD card with slow read times. SanDisk cards are usually prone to this. If you're able to buy a new micro SD card, I highly recommend this one.
Another reason could be that you're using a file-based EmuNAND and not a partition-based one, if you're using an EmuNAND at all. However, partition-based will still be slower than reading from the flash NAND.

Q: Am I able to add mods without constantly taking out my micro SD card?
A: Yes, you can! By using an FTP client, you will be able to send files to your micro SD card over the network. While this does require being connected to the internet, if you have 90DNS setup for your network, it will reduce telemetry sent to Nintendo, but you will be unable to access online features and the eShop.
I personally recommend sys-light-ftpd to use anywhere, anytime. However Ultimate Mod Manager has its own FTP server you can access by backing out of the mod installer and pressing Y to enter the FTP server. From there, you can use your FTP client to access the server and send files and/or folders.

Q: Why are my mods not showing up? / How can I perform the archive bit fix?
A: This may be due to the unwanted enabling of the archive bit on mod folders, which is a file attribute that indicates if a file has been backed up or not. The usage of this on a folder is how the Switch can read split files as one file. There are a couple ways to go about fixing this:
1. If you use Hekate, you can unset the archive bit for most files and folders there. Traverse through "Tools > Archive bit • AutoRCM" and select "Unset archive bit". This will unset the archive bit on everything on your micro SD card except the Nintendo and emuMMC Nintendo folder, if applicable. From there, you can launch Atmosphère and your mods should be in the list.
2. You can run a command on the mods folder to unset it on all subfolders.

For Windows, run this Command Prompt command in the /UltimateModManager/mods/ directory:
attrib -a /s /d
For macOS, run this Terminal command (replace [SDVOLUME] with your micro SD card's name!):
chflags -R noarch /Volumes/[SDVOLUME]/UltimateModManager/mods/

Q: What can I do to avoid getting banned?
A: Please take a look through this part of Nintendo Homebrew's Switch guide. If all you plan to do is mod Smash, then you should be fine for the most part. Just do not upload anything showing off modified content whatsoever.
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  • Skullkandy64 avatar
    Skullkandy64 Joined 4d ago
    access_time 4d
    I tried unistalling mods but now all i get is loading on the nintendo switch screen.It was working perfectly one day then when i tried to add more mods it crashed now it wont load.How do i unistall all of it? So i can get my game to load.I have no back ups in the back up folder because i tried unistalling it already but i didnt work.I need help please!!!
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  • Charmilly avatar
    Charmilly Joined 3mo ago
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    Hi ! I need some help please : I downloaded the mod "Random Size Modifier" (a mod with a .elf file) by Vishera, I put it in "SaltySD/ plugins/01006A800016E000" but when I start matches, the sizes don't change (the mod don't work) could you help me with the problem please ?

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  • WannaBeDev avatar
    WannaBeDev Joined 2y ago
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    access_time 11d
    I'm trying to open my data.arc in CrossArc, but an error pops up saying that System.OutOfMemoryException was thrown. How can I fix this?
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    A Question, how do you know which skin is c00, c01, c02, etc... is there an image that explains it...? thanks! i'm very lost in that
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  • Macadav avatar
    Macadav Joined 22d ago
    access_time 22d
    Everytime the game tries to load a .elf file it crashes. I looked in saltysd.log and kept saying "SaltySD: failed to load plugin `01006a800016e000RandomAngles.elf'!", why does this keep happening?
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  • Mario and Sonic Guy avatar
    Mario and Sonic Guy Joined 4y ago
    See ya later!
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    access_time 25d
    I was recently trying out a SaltyNX code, but the game ended up crashing when I booted it. And just to be clear, I did make sure that the .elf file was made correctly (no error reports during the .elf creation process), but I guess that didn't even matter in the end.
    Texture & Moveset Editor
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  • Linker7504 avatar
    Linker7504 Joined 28d ago
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    I am using Python 3.8 and it says whenever I try to input the correct offset version that  no offsets file corresponding to version "2.0.1"
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  • Linker7504 avatar
    Linker7504 Joined 28d ago
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    Does UltimateModManager recognize .pad files without a folder? I am trying to download the dark bowser skin and there is no fighter, ui, sound, etc. folders. The skin is by Julian0555.
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  • Myzotendo avatar
    Myzotendo Joined 2y ago
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    How can you make mods for SaltyNX/SaltySD?

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  • IceyJ avatar
    IceyJ Joined 28d ago
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    How can you tell if the mod/skin is online safe?
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