Just thought I'd pop in again to let you all know that modding, probably the most requested feature since release, is now in the game!
The new modding screen works by allowing you to update each fighter's attributes. You can also add new fighters and remove existing fighters.
Once you're done, you can save the entire database into a separate file and use it when starting a new game.
I've added a video to demonstrate:
Give the game a try and let me know what you think!