trogau

You can query core, plugin, and themes individually, or check all at once.
It defines four new methods:
<ul>
<li>xmlrpcCoreUpdateCheck – checks core, returns true/false</li>
<li>xmlrpcPluginUpdateCheck – checks plugins, returns true/false</li>
<li>xmlrpcThemeUpdateCheck – checks themes, returns true/false</li>
<li>xmlrpcUpdatesCheck – checks all of the above, returns an array of trues/falses.</li>
</ul>
The plugin was created primarily for WPUpCheck (http://trog.qgl.org/wpupcheck/), a simple 
Windows application that remotely polls a WordPress site to see if updates are available.

XML-RPC Update Check

This plugin provides XML-RPC methods for checking the update status of WordPress websites.

gr8nilay

This plugin is use to disable all your theme updates as well as notifications for the same. It will prevent your wordpress to check for new updates for each theme. This plugin is ideal for whom who have customzied the theme and won’t loose their customization at time of update.
Read This First: 
You need to keep your WordPress updated with themes and plugins so if you fail for the same then it will might compromise security of your site.

Disable WP Theme Updates Advance

Easy to install and automatically disable all theme updates.



Nice..!!

Disable all your WordPress theme updates on plugin activation.

XML-RPC Update Check vs Disable WP Theme Updates Advance