Below are skills required for the Back-end Developer role:

Mandatory Skills:  ASP.Net, Database Technology (MySQL/Oracle/Mongo DB),  PHP
Good to Have Skills:  JavaScript, HTML 5, CSS

Below are skills required for the Front-end Developer role:

Mandatory Skills:  HTML 5, CSS3, PHP, JavaScript, Testing and Debugging, jQuery
Good to Have Skills:  AngularJS/React JS (from extra research), SEO principles

Below are skills required for the Full Stack Developer role:

Mandatory Skills: HTML/CSS/JavaScript, Database Technology (MySQL/Oracle/MongoDB), ASP.Net,Testing and Debugging
Good to Have Skills:  AngularJS/ReactJS

Tip: As you see, the roles and responsibilities of a full-stack developer is the combination of a front-end and a back-end developer. This also implies that the mandatory skills for a full stack developer increase.