Oda had the PERFECT opportunity to give her a fight during Dressrosa with Diamante. The dude's DF power made him able to bend his body like a flag, making him like the absolute perfect opponent for Robin. He's not a Logia so he's not invincible to her, but his ability makes him have some resistance to her just going 'CLUTCH!' and him being defeated instantly. Like seriously, he was the perfect opponent for her to get in on a fight with.
And what does Oda do? Have her stand back and "protect" that worthless piece of garbage Rebecca while Kyros fights him. I get Kyros being in the fight too and even getting the final blow, but Robin should have at least been tag-teaming with him.
Robin is my favorite SH and in the leadup to that chapter I was soooooooooo excited at the prospect of Robin getting a fight and I got massively disappointed. I almost feel like Oda had intended for her to fight Diamante but backed out of it at the last minute, with the way everything was being aligned up until the actual fight. After this fiasco though, I gave up on my favorite SH getting any fights and resigned myself to expecting her to be just fodder cleanup for the rest of the series.