Generating Content Type at once It is very time consuming to define fields, set their types and validation while creating a content type. It's a nightmare if the fields are exceeding in numbers (say more then 10).

Is there any way to define all the fields, their types, structures, validations one time on a page and generate the whole content type at once?
There is none, and there probably will not be one. Drupal is modularised, pluggable system. Each and every module can provide it's own field types, validators, widgets. They have custom settings defined in their modules. There are per field settings, and settings specific for a field in a given content type. Module to provide it all on one screen would need to know about all these modules and their form elements, and there are no hooks for that now. It would be a big job to hack it together with what's provided.