This is a tough one... Hmmm...
Both are pretty good analysts. Marcy leans more into the book smarts from what I can tell, and her not having an A in gym shows that she isn't exactly the best athlete. Basically unless the Core wants her ass, I ain't sure how much of her smarts aside from adaptability and knowledge in Amphibian magic works. Sure, Marcy is the smartest character in the series aside from maybe the Core due to it somehow figuring out how to manipulate her, but she isn't exactly Sasha who is more focused on the art of
war.
Deku, on the other hand, puts his analytical skills more on the combat aspect, analyzing each quirk and their weaknesses, although fiction doesn't seem to like showing drawbacks unless it needs to, so I dunno if he's getting too much on the weakness spectrum from Marcy besides "she's as clumsy as a drunken uncle," even though the AP gap between the two is essentially "Marcy can murk Deku in arm wrestling." Deku's lifting strength would put him at a major advantage over Marcy, so much so that I dunno if kneeing Deku in the groin would do Marcy any favors if she gets pinned. Also, Deku has better ranged options than Marcy...
See, Deku only gets the piercing damage part of the fire arrows because Deku could resist 5000 degrees celsius while Marcy's fire arrows could only do 1100 (
https://www.thoughtco.com/why-is-fire-hot-607320 ) due to it being a wood fire. Smoke arrows aren't doing much either. Stinkshrooms are Marcy's best option since they are corrosive (bear in mind, All Might himself couldn't use One For All that much since one of his lungs were utterly destroyed), but they take five minutes to grow and by then Deku would've figured out how to.... Stand back a little further. Deku, on the other hand, can just use his fingers on the fly (well, literally anyone can, just Deku's fingers are more combat applicable than the average human fingers) with the only detriment being potential injury to himself from doing so.
So yeah, more than likely Deku's winning this than not.
