I'd just like to issue a couple warnings to all people wanting to use mods in Smash Ultimate real quick since it is much more dangerous than Smash 4 and I've seen a couple people wanting to go online with mods (unfortunately that won't be a good idea in Ultimate).
Here's what you need to know:
1) Stay offline at all times while in LayeredFS. I don't mean Airplane mode either, I mean you should delete your internet settings since any connection to the internet is a risk when playing with any Switch CFWs.
2) LayeredFS (the CFW method used to load Switch mods) is very detectable by Nintendo and has ties to piracy. If you connect to the Internet while in LayeredFS there is a 90% chance of you getting banned and I'm not talking just from Ultimate's online, I'm talking about from all Nintendo services including, but not limited to: game updates, system updates and the eShop.
3) Make a Nand backup BEFORE modding your Switch. This simple, yet long, process nearly eliminates all ban risks related to Switch modding and homebrew. (I'd recommend finding a guide on Gbatemp myself)
This is perhaps a stupid question, but I have two Switches, one of which will never be connected to the internet. Am I able to do a local account transfer between the two consoles so I can keep my Ultimate save intact? Would Nintendo be able to detect anything if/when I move my account back to my online, non-hacked Switch?
more of a clarification than a question, but i have been connected to the internet all the time when using layeredFS/atmosphere, not yet for Smash modding, but for other games. so i have been at risk of banning the entire time? (i have yet to actually go online in any game while mods are on.)