Comment on Stallion WordPress SEO Plugin by SEO Dave.
The Yoast plugin doesn’t include many SEO features, those which are important are included in Stallion Responsive either the same or better, so there’s nothing to gain using Yoast with Stallion: I don’t use the Yoast plugin on my sites for example.
So Stallion theme users shouldn’t use Yoast.
That being said I know some will still use the Yoast plugin with Stallion, so I’ve tried to take this into account, but some of the Yoast features break important Stallion SEO features, so be careful.
Since you posted on the Stallion SEO Plugin page, the Stallion SEO Plugin (which is free and can be used with any WordPress theme) can be used with the Yoast SEO plugin to replace the damaging Yoast features.
Yoast isn’t a particularly good plugin, unfortunately the author refuses to follow best SEO practices and includes damaging SEO features (nofollow and noindex) without warning the user.