Uhm... seems alright but here one thing that I am gonna edit:

Elementals are creatures, mainly humanoid creatures. They can be technically demonic, earthly, and holy, but for this we'll just consider them earthly with a broad range. They are made up from one or two elements. One element would make that element strong, two elements would be a medium-weak version of both elements. They really don't have any specific gender, as they are made up from elements, and they also are weak to whatever element(s) counter its main element(s). Because of it's lack of organs, it has no need to sleep, but can be put into a stasis mode, either by their creators, or if they lose enough energy. They do not reproduce, they are created through a strong force of one element, mixed with a bit of it's creator's intelligence. It feeds off of its main element, and when it feeds it gains energy that makes it's power stronger, [b]though if the elemental is not prepared for the new energy, it might go out of control.[/b] A main element is either it's only element, or it's primary element if it's made from two elements. If both elements are it's primary (eg. an elemental with ether/darkness powers using both of them to an advantage 

That last part added is just to make it that a elemental will not go absorb a huge furnace energy and become really too strong. It would need practice and slowly mastery of its form to become stronger... How you think about that?