By default WordPress will show all sub-category members and posts of a parent category in a category specific template. There are any number of techniques to control how the sub-category members are displayed, and a few relevant plugins to address this matter.

here is a good jumping off place but this may be too much effort for the result.

this plugin has the opposite approach in that it excludes sub-categories from an assigned parent category view

But nothing I can find shows a clear way to create a sub-category specific template…. meaning that any sub category archive display would be presented with the parent category template. Since there seems to be no way to define a specific template to a sub category, none of the above seems worth the effort since you could do the following and achieve the same end result:

  • Create a false parent category like “media”
  • Create a true parent category like “genre”
  • Create a series of sub-categories that are attached to the “true parent”
  • Use the 3.0 menu module to create direct navigation to any sub-category you want to show
  • Then each sub-menu will display in its’ parent template

Of course this means that the display in the “false parent” display will not be automatically generated as the “true parent” information is updated, and that it may get very muddy if you want to show multiple “true parent” members in the “false parent” display via multiple category check offs….. but if all you want to do is create a master category gateway to sub-category selection this will work just fine …… especially since you have to live without a sub-category specific template anyway!
The argument could be even made that having the display of subcategory “gateway” information offers a great deal of extra control for just a little extra effort
Of course if a “true parent” template is never defined in the first place, the sub-category display will be set by the archive.php file

While navigating directly to a sub category is possible, the syntax for that link seems slightly counter-intuitive.

You would think that this would work: http://plasterdog.net/code/z would work, but it doesn’t
This is the syntax you have to use: http://plasterdog.net/category/code/z inserting “category” at the top of the chain is mandatory