TG stands for transgender, and TG transformation is implicitly “transformed gender”. It is when an individual transformed from the birth gender to the other gender. It also refers to pictures, like fan art. Additionally, fan art illustrates a character of one gender transforming to another gender.
When discussing TG transformation, TG art is always associated with this. TG art is popular to where it’s even shown on the most popular animated programs sometimes. With this said, a plethora of TG works are not sexual in nature. They are done for humorous or creative purposes. TG art uses mostly males. Also, in a lot of TG literature and art, the victim is so satisfied with their new form that they decide not to change back even if there is a cure.