I also dual-main both Lucina and Min Min. I disagree with the "vastly different character archetype" that tends to float around.

I think, once you learn Min Min's unique control scheme, piloting both characters isn't that hard for the player. The general game plan is to use safe, aggressive disjoints to push the opponent up and out, where both of their character's elite edgeguarding rack up enormous damage or take/steal stocks. The way you do both are different, but it's actually not that difficult to switch between the two, especially because both characters are relatively simple.

It's actually way harder for the opponent to adapt, because their threat bubbles and timings are different. While I'm nowhere near Proto's level, I find that I have a much easier time sticking to the gameplan despite switching than the opponent has trying to figure out how to break it.