Marco - From what we saw, Marco doesn't seem to avoid attacks like all other logia do (damn luckers, unfair advantage!). He takes them fully, and then his body recreates. However, we currently don't know if he feels any pain when being hit, or what limitations his ability has. Oh, and of course Marco can use haki!
Teach - BB's fruit is certaily awesome, but it's particulary useful against fruits that reduce or nullify damage (any logia, Luffy's gomugomu, Mr.1's supasupa, Jaws' diamond, etc). On the other hand, it wouldn't be so strong against a power like Flamingo's, Foxy's or Perona's. Sure, the gravity effect would still be very useful, but it would be nowhere as dominating.
So before even thinking about who of these two would win, we should know something more about Marco's fruit.
- If it acts like a logia and only nullifies attacks, then BB's power will be as effective as it was against Ace.
- But if it regenerates Marco when he gets hurt, it means that BB should hold him the whole time to neutralize his power! If Marco can stay away from BB a couple of seconds, he would completely regenerate! Not an easy task there for BB.
My vote goes on Marco, but we really know too little about him...
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