Japan's early superhero Ogon Bat has an evil doppelganger called Kurayami Bat and he's basically a skull headed badguy so I shouldn't have any trouble with him this Italian herohttp://www.internationalhero.co.uk/t/tanksitalia.htm
looks like he might be supposed to be Japanese or have some connection to Japan? Great name and created about the right time that if he had pre-existing adventures it could have involved him in the war... a bit sad his costume isn't the sort of "super I'm really looking for. I'm clearly going to have to use heroes for war time villains, the bad guys just aren't as well documented it seems.
But then there is a war on.
These guys seems like they have potential http://www.internationalhero.co.uk/u/uomoblindato.htm
The armoured hero could, with the war as justification for and armour upgrade, be a not Iron Man if worst came to worst.
The fat Mussolini looking guy would make a great heavy for the Italians but his Atomic Man alias suggests his origin is probably post war.
German heroes from this era seem a bit scarce (probably for the obvious reasons),I'm sure I'll find a red skull metalfig, but two skull faced villains...?
The bad guys are lacking a bit in the tights department though.
a skull faced demon-thing from japan, another bone head from Germany, a living tank from Italy (or maybe japan?), an armoured tech hero for Italy, And maybe
a nuke powered Italian strong man, well it's a start of a villain team I suppose.
Is Katana supposed to be a hero or a villain? I could probably justify her inclusion somehow.