Bamm will probably be able to do it, since FUG's wish is exactly giving him more power to become a slayer.
My point was: Enryuu can do it, but can Zahard do it too? If he can't his point in chasing down Po Bidau family would be to weaken Gustang and not actually to kill him, but Zahard is still a mystery we don't know which sort of contract/conditions he had with adm. and why he locked upper floors (I mean, could it be he has powers to kill adm, but never used it for some reason? I doubt it, but...). SIU also stated Gustang is an antagonist, so maybe this fight has more it (besides Enne) or it's just Zahard trying to catch a traitor rat