If youre impatient like me, this if for you. These nvrams unlock all the hidden characters right away.
This one is for MAME and includes tekken3/tag, DOA, Soul Calibur and Ehrgeiz. Just place theses folders into your mame nvram folder.
http://uploaded.net/file/7hitcf3bThis one is for DEMUL and includes Marvel vs Capcom 2 (for usa and jpn bios). Do not copy the folders, just the files that corresponds to your version.
http://uploaded.net/file/fdrisgeaIf anyone has others to add, please post them for lame people like me that play too casually to unlock them the hard way.