Another one of those simple questions that unfortunately doesn't have a corresponding simple or "correct" answer. Many that use a platform style don't even get anywhere near the "launch" stage while others get well into the air. Weight shift can be an important aspect of hitting a tennis ball or any other ball. Doesn't mean that you cannot hit a ball without the transfer of weight, just might not be able to hit as well. I think the best situation is having the right foot pivot enough to bring a weight transfer up through the serve.
