I’ll leave this stickied until the servers shut off on the 8th, 4pm PDT.

Important note, you do not need a modded 3ds / wiiu to do this.

However, from my experience, if you do have a modded 3ds, the process is really quick, and I highly encourage doing it. If your 3ds already has universal updater, and is connected to the Internet, downloading the tool and running it takes like 5 min. The tool also uploads the data for you, so once you run it, your job is done!

Thank you DreitonLullaby for bringing this to attention!