I have PG but they don't seem to be eating bba in my tank. I can tell by the way they graze. PG graze like any sucker mouth pleco, so they are good at erasing green dust algae on glass and leaves. SAE nibble on the leaves and along the edges where bba concentrate.Panda garra are said to eat BBA. I think mine do but I'm not 100% sure I have black beard algae. Cory of Aquarium Coop said several.in Michigan told him of panda garra eating black beard algae.
Molly nibble on leaves like SAE, so may have minor impact on BBA. I read that American flag fish eat bba, but I have never own them to verify.