Yeah me too! I love the way they fight, but I find myself annoyed by nana constantly following me and me dying when she's not there(because of belay), not to mention that they look kind of awkward when they overlap each other, which happens often. Rosalina is different, she doesn't need luma for recovery, luma is a good distance from her so they don't overlap, and luma can be summoned again if defeated, really he's more of a weapon unlike nana who is half of your strength.
I think they would have slightly poofy bellies, not exactly fat but getting there lol,
or they would look like this. . . . . .