Depends on which parts you like from each aesthetic, you could put them together in different ways. for example, pastel goth uses a lot of cartoon motifs, you could make the fairycore motifs ( flowers, cute animals, plants, butterflys etc) and make them cartoons.
Another example could be pastel goth with more greens. pastel green and black cute fits? yeah, depends on what you want from the outcome really, whats it for?