What are the regulations of gymnastics?

There are way too many to list. It changed for each apparatus. The basics are.

No lyrics in floor music, no underwear showing under leotard, no shorts ontop of leotard, you must complete a skill, if you fail to complete it you lose points, you must not fall off the apparatus, music is only allowed for floor, you must compete in floor, bars, beam and vault. There just some of the basics, there a many more.