Thinking about endgame matchups... I think I'd agree that for the most part it won't be 1v1s. I'm feeling Gigantomachia vs. Kirishima/Mina/Others. This one's pretty well set up. Machia is a multi-hero threat, Mina and Kirishima have history with him. Then, Todoroki vs. Dabi/Geten to reverse the dynamic - he's gonna end up a major power in his own right, so you pair him with Dabi (for obvious reasons) and Geten (to complete the power symmetry). Unless Shiggy ends up giving Geten's power to Dabi at some point... could be cool. I could see Uraraka vs. Toga, but I'd agree it's not a great pairing as is. Needs more groundwork done first or else it'll just be a designated girl fight thing. Yeah, they both like the same guy, and Toga is also a little obsessed with Uraraka, but the first is thin and the second hasn't really been explored much. Shiggy vs. Deku is pretty obvious, might have Bakugou in there too, maybe.
But I think that we'll start seeing the cast open up a bit after this arc, on the villain side especially. We got that setup with the PLF lieutenants that hasn't amounted to much yet, but I think we'll get more of them in the future. So all this could be pretty easily subject to change.
Shiggy needs a set #2 btw. Somebody for him to bounce off of.