The past history of Shalla-Bal mirrors that of her Earth-616 counterpart.
In recent history when Franklin Richards was turned into a new Galactus, the Silver Surfer was charged with ensuring that this new incarnation of the world eater was more humane that its predecessor. During their travels, through reasons that remain unrevealed, Shalla-Bal was turned into a Silver Surfer just like Norrin Radd. The two would act as heralds for this new Galactus. When Galactus was called back to Earth to battle the Celestials that arrived there to pass final judgement on Earth.
There, the Silver Surfers tried to help Galactus stop the Celestials, and during the fight Shalla-Ball was killed by the Celestials. The devastated Silver Surfer would mourn Shalla-Bal on Earth after the Celestials defeat within the Human Torch erected in New York City. When the Surfer sacrificed his life to give Mar-Vell the Power Cosmic, his soul was transported to the Realm of the Dead.
There he was reunited with Shalla-Bal, their current whereabouts are unknown as they have not been seen since the death of Death.
Powers and Abilities
Shalla-Bal presumably had the same abilities as her Earth-616 counterpart. Presumably, when she was transformed into a Silver Surfer by either Galactus of Norrin Radd, she probably gained the same powers as the Silver Surfer.