Any move is allowed unless it puts the dog or handler in danger, and the dance routines typically include the dog doing twists and turns, weaving through the human's legs, walking backwards, jumping, and moving in sync with the human.
This sport requires mastery of basic commands, and before putting a routine together, the dog must learn each individual move. The dog must also be able to work on both sides of the human's body, not just the left as in standard obedience training.
This is a sport better seen than described. Here's a video clip from Britain's Got Talent!