blackbeard can take away someones DF abilities if he has physical contact with them. someone like Enel would just teleport away. then with his lightning he can take out BB since his body can take damage.
logia vs logia is complicated and kinda reminds me of pokemon in how some logia are vaulnerable to some other specific logia. but when one ability doesnt "by nature" dominate the other it seems its really up to how strong and determined the users are, for example Ace vs Blackbeard where BB was just stronger.