@Hinscher:
Also to those saying Robin is too weak. I think Oda has underused her fruit. He instantly nerfed her when she joined the crew. I think after 2 year arc its time to un-nerf her.
Besides the only Strawhats standing right now are Luffy, Zoro and Robin. Most arcs when it comes time to takign on the enemies we have to worry about giving 10 people spotlight. There is only 3 people right now. If he can't find the time to give Robin some spotlight fighting I am going to be severely disappointed.
As for Trebel. What is one thing that most enemies have in regards to being beaten? When looking back you can always think, "wow, that was like the perfect matchup. Only that strawhat could have beaten him" Now lets look at Trebel as I said. What are his strengths. Sticky fruit and immense strength. We've seen that his sticky fruit can stick even the hardiest warriors like Don Chinjou and the other combatants. He is also able to throw battleships around.
Now lets look at Robin in comparison to those two skills. She did state back in Arabasta that strength means nothing to here, but I'm sure someone will quickly show Zoro's zombie on Thriller bark. Two things to that. 1. It's been 2 years, she is stronger. 2. It was a Zombie and they can do feats normal people can't such as easily allow a shoulder to dislocate, ect cause feel no pain. Now also consider strength means NOTHING if it can't hit the opponent. Robin can be hiding behind a wall and use eyes to see and attack that way. Have clones all aruond, ect. Many ways to never actually be hit. I have seen zero evidence that Trebel has good CoO or any way of determining where Robin is.
Then on to the other strength of Trebol is his sticky goo. Basically the same as the above argument for his strength. If he can't sticky her real body then its pointless, even if he stickies her real body, she can still create clones and arms and so on I would think else where to continue to fight.
Her fruit is almost a natural enemy to his. The only problem is finding a way to take him out since it appears only Luffy/Zoro/Sanji have Haki. But Luffy has taken out two Logia's without Haki before. Maybe its time to see her take out a Logia by her smarmmts/skills now.
I want as much as any other person here for Robin to defeat a major opponent, but I don´t think it will be Trebol. Still sticking to Sabo defeating him for several reasons. Him crashing down right next to him now, and Trebol also said his sticky-glue-thingy was flamable. We haven´t seen it combust yet as far as I can remember, and if you are familiar with the term "Chekhovs gun" it should combust sooner or later. Also holding a spot open for Ussop as he has some flameable attacks. Although he is pretty beat down at the moment.
Edit: I completely agree jack1000