In addition to the aerobatics mentioned in the title, I would also be interested into formation flying.
Is there a specific licence to be acquired? Does a licence covers both? What are the requirements?
The appropriate rules are in FCL.800 Aerobatic Rating
So there is no specific license to be obtained, however there is a specific rating, which is just an endorsement in your logbook.
Its not clear from the documents that I've read that formation flying qualifies as aerobatics. Some other countries don't consider formation flying an aerobatic operation.