I made a (mostly) video game centric character pack for personal use:
https://mega.nz/file/SeAjXTbD#xxvFNsVII7vVLP7iKaI3j8IZb1uMgeykKXVayYCce2k
Just unpack the .zip file and then load it.

Works with online. Keep in mind that this pack is very primitive; I don't know how to swap the audio and icons of the custom characters from the originals, and the only one that has custom audio for whatever reason is Osaka. If someone wants to edit it to fix the audio and icons feel free to do so.

I've played for a few hours with it and noticed nothing out of the ordinary, with exception of >>714005792 where the game would crash on me upon the map being loaded.
I have no fucking idea why or what caused it to happen. After fucking around with it for 1 hour I only managed to crash it during the lobby match and once while playing Grand Prix, then never again. I even checked all characters in Time Trials and even did a bunch of Grand Prix rounds (Thank god the map is the first race) and not once did it crash on me. The only thing I can think of is that it might just barely go over the polygon count where the game can't handle it anymore, but I have no knowledge in MKWii hacking so I can't confirm this.

Have fun fellas!