So these are unique mods, as they require Ps1 Emulator Duck Station. To play with them you need to replace textures. This Video is a perfect tutorial on not only how to create mods yourself but to also add these mods into the game! for a slight TLDR:

Find/create a folder you want to use for your mods

In Settings -> Graphics -> Texture Replacement: use that folder for your search directory

Add the folder "SLUS-20328"

Extract the mod folders in that SLUS folder, so within it should be just dump and replacement

check the "Load Texture" option back on the emulator and enjoy :)

These costumes include:

Baki Hanma → Bruce Devil Kazuya (Half Human) Ganryu → Hulk Heihachi → Demon Jack → Iron Man Lee → Silver Surfer Paul → All Might King → Venom Wang → Steve (Minecraft)