Shimmer has one super ability -- she can transform any physical object or substance into any other element or substance. In Mighty Protector terms this is the Transmutation ability (see p. 76). Any transmuted Gear gets a save to resist based on its Gear BC. Any other substance transmuted gets an EN-based saving throw based upon its mass. Find its weight in the ST Carry column of the Basic Characteristic table and read across to the Saves column to find its save.
The Transmutation ability has a (+10) modifier for more than one target, in this case "any physical object", but it doesn't have a modifier for turning those targets into "anything". For that I gave it another (+10) modifier.
Shimmer's one super-power blows past the Ability Cap for her 150 CPs, but there's really no way around that, and honestly... she's not overpowered.
In MP game mechanic terms, what effect Shimmer's transmuted substance has is up to the GM, but if its a damaging substance, like a poison or chemical, the saving throw penalty should be at least as good as the standard attack for Poison/Venom, with an EN save @-8. So when she turns an object into Ether gas, as she does in Teen Titans #3, everyone in the Area Effect should get an EN save @-8 or fall asleep.
Of course, she doesn't always have to use her power in a damaging way... she could just wave her hands and make any Gear in her area effect turn into air... or turn a section of wall into vapor. Her ability is limited only by the imagination of the GM running her.
Shimmer MP Sheet
Shimmer Cares for Mammoth
Shimmer Makes a Room Full of Ether
Shimmer is a trademark of DC Comics. This write-up is by B.K. Adams. Mighty Protectors is a trademark of Monkey House Games