Light Clay to boost screens in my opinion.
The purpose of a dual screens Pokemon is to set up your screens as quick as you can. Bronzong has a nice defensive typing so just give it EVs in Defense and HP and give it an Impish nature and it should hold out from physical attacks, at least for enough turns to set up both screens. You don't need to kill a Pokemon if you're dual screening, although it'd be nice, it's not necessary so there's no need for a Silk Scarf.
After setting up both screens, just use explosion and you're good to go to your next Pokemon.
