I think the Hughes-Hronek thing is an exhibition in why this isn't exactly a straightforward question to answer. There are certain things that pretty reliably work, at least "on paper". But there are also certain instances of two defencemen who
should work well together on paper and complement each other perfectly...and then it just doesn't work at all. There are also things like Hughes-Hronek that doesn't make a whole lot of sense on paper...but just put together an absolutely massive season as one of the most ice-tilting pairs in the league in tons of tough minutes.
Chemistry is a funny thing, and it can account for a huge amount of how good a pairing is, or can be. Whether it's "more than the sum of it's parts" or "oil and water". And it's not always immediately evident until you actually try it.
That ability to process the game on the same "wavelength" or take that similar approach to the game, can really make for pairings that elevate both partners. Ideally, you've got a decent mix of more offensive and defensively oriented inclinations...but that "on the same page" element overshadows a lot of things.
It doesn't even have to be two really "smart" players like Hughes-Hronek. Sometimes just putting two lunkheads together works remarkably well too. Counterintuitively so. Where they just wanna play rolling forward, step up and pinch aggressively, and rattle the boards and obliterate guys whenever possible...and somehow that translates to a telepathic ability to read one another's one-track mind, and adjust to exactly what their partner is going to do. Because it's exactly what they'd do.
So yes. Sometimes opposites are complementary. Sometimes the same is complementary. Sometimes things that seem like a terrible idea end up complementary. Sometimes things that make all the sense in the world on paper, are just an absolute trainwreck.