Create view file with your template name - CategoryTemplate.MyCustomTemplate.cshtml in Themes> YourTheme > Viewes > Catalog. Also create same file at Viewes > Catalog folder.
Here CategoryTemplate.MyCustomTemplate.cshtml is your custom template.
Now you need to add category template in admin area.
So go to admin > System > Templates > Category templates and add here new template with viewpath- CategoryTemplate.MyCustomTemplate
Now go to Category edit page of which you need to change template
You can see new added template in Category template dropdown.
Select your template and save category.
Same for Product, Manufacturer and topic will work