WordPress has minimum theme template files as
and also some other files as listed here.
If the theme developer wants to build theme with less bells and whistles, what are some of the template files which should be included at minimum? There isn't any guidelines in the WordPress codex. Only thing that you can find is what files and when to include them. For making use of most of the WordPress functions without any conflict, there doesn't seem to be specific number mentioned for number of template files.
So how many files should be there when you build a theme from say raw html template?