On sonic unleashed how do you a moon jump?

You can't perform a "moon jump" in Sonic Unleashed. The game doesn't have a specific move or technique called that.

It's possible you're thinking of the "Homing Attack", which lets Sonic target enemies in mid-air and launch himself towards them. You perform this by pressing the "A" button (or equivalent) when in the air.

If you're thinking of a different jump-related move, please provide more details so I can assist you better. 😊