1. Visual Composer plugin

https://github.com/WP-API/WP-API/issues/2578 - Just add the following code to File: wp-includes/rest-api.php at the bottom

/**
 * Modify REST API content for pages to force
 * shortcodes to render since Visual Composer does not
 * do this
 */
add_action( 'rest_api_init', function ()
{
   register_rest_field(
          'page',
          'content',
          array(
                 'get_callback'    => 'compasshb_do_shortcodes',
                 'update_callback' => null,
                 'schema'          => null,
          )
       );
});

function compasshb_do_shortcodes( $object, $field_name, $request )
{
   WPBMap::addAllMappedShortcodes(); // This does all the work

   global $post;
   $post = get_post ($object['id']);
   $output['rendered'] = apply_filters( 'the_content', $post->post_content );

   return $output;
}

2. Photo gallery

(to be continues)

3. Contact Form

(to be continues)

4. Ads banner

(to be continues)