Hi,
Usually, feather picking has two causes:
One, not enough protein in their diet. An all-flock has usually 20% protein vs. layer feed that's 16-17%. If you don't feed this and switch to it, it has less calcium so we put out a dish of oyster shell for the hens.
Two, overcrowding. Chickens need 4 sq feet per bird in the coop, and minimally 10 sq feet per bird in the run, 15 sq feet is optimum.
If it's just pecking, and not pulling out feathers, I'd separate the bully for a few days and see if her attitude changes.
How old is the one doing the pecking? I highly doubt she's not laying because she's a bully. There's got to be another reason for it. I might try giving them vitamins in their water every other day for a week or two to see if that helps with the laying. We use Poultry Cell, but any full-spectrum vitamin/mineral made for poultry is fine.