In Final Fantasy XIII-2, Serah carries a Moogle with her. It serves as her weapon in battle, but that's not all!
The upcoming issue of Jump lists three examples of things you can do with the Moogle:
Moogle Hunt: Tell the Moogle to search for things. When you see a flash above its head, you'll know that there's something hidden.
Moogle Toss: Once you've developed stronger ties with your Moogle, you can toss it long distances to get treasure boxes.
Moogle Clock: When the Moogle detects an enemy, a clock-like gauge will appear on the screen. If you press circle within the time limit you can get a pre-emptive strike or choose to flee.