In all Marvel/Sailor Moon fusions that I’ve seen, Ami takes the role of Spider-Man, the hero that has the most character traits in common with her. But really, there’s a couple of others whose shoes she could step into, most notably, Iron Man. Aside from the playboy side of Tony Stark, they really do have a great deal in common.
Genius, overwhelming sense of personal responsibility, the willingness to lay it all on the line and take the risks so no one else has too. Aside from the playboy characteristic and that could easily be a front for Ami, its very possible to imagine a world where a Teenaged or young adult Ami builds a set of armor for herself and puts up a front as a socialite
"Ice Queen" to divert attention from the fact that no one has ever seen her and the mysterious Iron Woman at the same time.
But even as Ami battles the terrorist organization known as A.I.M, there are other enigmas surrounding her. Such as the green haired woman with the two cats who seems to know more about her than she does. Or the man in the mask and tuxedo and his gang of sailor suited women who are tearing the city apart looking for something … or someone.
Above them all is the sense that Ami can’t shake, vauge dreams about an evil force, and rumors in the dark, whispers of a single name that drives fear and terror before it like a rampaging herd of cattle on stampede. The name is Beryl … and Ami may be the only thing in her way …
Something like that. Beryl would take the place of the Mandarin in this, obviously, but I haven't come up with why Ami would build or put on the suit in the first place.