Models propagating a single extra degree of freedom are very popular as Dark Energy candidates. Examples are Scalar-Tensor, Vector-Tensor, and bimetric theories of gravity. Despite their common properties, these theories are usually described in different frameworks. I will show a method to construct general parametrizations to describe the linear dynamics of all these models. I will present the results in a unified formalism, and discuss under what circumstances it is possible to have a unified description for all these theories.