Normally you will like to generate a file for each entity/class.  Use the BaseExample.tt

 

Steps

1. Open the CodeGenTemplates.sln file
2. Create a new Folder for the template under Languages
3. Create a new T4 template in the newly created folder
4. Copy and paste the contents of the Example\BaseExample\BaseExample.tt into the newly created template.
5. Make the desired changes to your template