Picket is an Al Bhed Watcher who resides in Bikanel with Nhadala and her crew, seen in Final Fantasy X-2. Because Picket is an Al Bhed Machina, it is fluent in the Spiran and Al Bhed languages. Picket looks like that of the Negator from Yuna's previous journey, and the three Watcher enemies.
Picket is a surveyor of the vast desert region, it normally flies around the island to see if anyone had gotten lost within Bikanel's sands and also notifies the Al Bhed if an expanse is safe to dig at or not. If there are people who have gotten lost within the desert and/or have fallen from dehydration, Picket alerts the Al Bhed diggers of the person's/group's location. It even has the ability to detect unidentified objects that might appear while digging in the sands. Because Picket is a Machina, it will not collapse from dehydration within the desert as it does not need to eat or drink to stay alive, no matter how long it or far away it goes from the campsite.
This ability of Picket's is seen in Chapter 1, when Rikku manages to get the Gullwings lost in the desert because she could not locate the campsite. The Gullwings soon fell to dehydration after walking a ways, and Picket happened to be there. According to Picket, the Gullwings were located at region B-5 of the desert.
Picket is also the escort of the Gullwings when they decide to go digging. However, the Gullwings are under a time limit. For safety precautions, Picket will not allow the Gullwings to go too far away from the hover. Early on, this limit is 10 seconds, but later, it is made 30. After the time has expired and if Yuna fails to get on the hover to exit the expanse in which the Gullwings are digging, Yuna will collapse from dehydration, and anything found during the dig will be abandoned.