Now this is the default sitecore feature to select all language in the publishing wizard in the newer version of sitecore.
But still if you are working on the old version of sitecore < 7.2, and want to implement the functionality where you can select all the languages on one click means Select All checkbox in the publishing Wizard? So I am here to help you for the same implementation by this blog.
So after doing some research i am able to give JS reference in the Publish.xml.
I hope this article will help you.