I think that Marisa vs Yuffie does, FF7 is still the most well known FF and Yuffie's probably next up after Tifa, Cloud, and Sephiroth, Kasen vs Fleetway Sonic counts if you view it as a version of Sonic (and absolutely doesn't if you view it as a little known version of Sonic), not sure about Remilia vs Rachel at this point since BlazBlue is both not at the peak of its popularity and on a bit of a hiatus at the moment, but I think it would actually eliminate Yusuke vs Reimu considering the lack of western knowledge on both franchises (if this was a Japanese show then I think both would be well known enough to carry an unknown). If a new BlazBlue is announced then Clash of the Noble Vampire Brats is back on the table.
As for others, I don't exactly like Flandre vs Marx but it definitely fits the criteria, same with Yuuma/Kirby.