This pastebin contains links to prepacked Mods for the UNDUB and an unpacked one. I'm not a packing an EU one and you guys can just do it yourselves.
I got a few (only a few) requests on Youtube asking for an update to when it broke the version someone linked to it in this thread: https://gamebanana.com/threads/200121
Also added a Japanese UI unpacked link.
The only reason I did this was it changes the *ENTIRE* UI and voices to the Japanese version of Smash 4... which is what I use for my 3DS. I am mainly a JP language player on the 3DS and I didn't want to start over on my saves or rebuy any DLC (or heck, THE GAME) when I had it for the USA version. All of these files were extracted from the readily available JP version update from the eShop.
The main detriment is this does not let you enter any hiragana or katakana in the name entry.