In another mod posted via GAMEBANANA, modder TheAggrivator has restarted work to fully add Adventures Krystal to Super Smash Bros. for Wii U. The mod will skin over Fox rather than Zero Suit Samus as in the NEOFilly Mod. It looks like the mod will be a bit more detailed than a simple skin swap. Additionally, this mod will eventually come with a custom Character Select Screen profile and possibly custom Krystal sound effects/voice acting.
The mod is still in development, but progressing rapidly. Keep an eye on the project page for more details as they become available.
Thanks to Smokey for the heads up.