Any SHUA Villain who has "Immune to Normal Weapons" or "Immune Weap < +N" is effectively INVULNERABLE to all physical attacks. This was done on purpose, with the idea that Heroes have unlimited castings of Magic Missile, Fireball, etc. and should be using those Super Powers instead of trying to bash away with their fists. The Heroes themselves can also have this INVULNERABILITY to physical attacks.
The only FRUA creature that I can think of which has BOTH "Immune to Normal Weapons" and "Resistant to Almost All Magic" is the Iron Golem. You can make some of the Items have magical bonuses, make Iron Golems vulnerable to at least one type of elemental damage, or avoid the issue by not including any Iron Golem combats.
Hmm. This does call for some thinking. These are just thoughts, raising possibilities, not conclusions:
Invulnerability in current SHUA uses the SpecAb "Immune All Weap." And since there are no magical weapons in current SHUA, that means "Immune Weap <+2" and "Immune Weap <+3" are unused (and would be redundant) SpecAbs.
But, if magical plusses were introduced into an expanded (and slightly revised) SHUA, those SpecAbs could be utilized. Perhaps a range of Invulnerabilities could be tailored, similar to how there are levels of Super Strength, say, to have "Invulnerability 1" thru "Invulnerability 3."
Now, currently, if a PC buys Invulnerability then they cannot be hurt by melee attacks, even from Bizarro or Black Adam. Maybe that's too
Invulnerable, even for a hypothetical "Invulnerability 3." After all, Superman was able to kill General Zod by using his super strength to break Zod's neck in the movie Man of Steel
. And in comics, Superman was beaten to death by the super-duper strong Doomsday.
If the proposed hypothetical "Invulnerability 3" (using the "Immune Weap <+3" SpecAb) still had a few melee weapons that could do it damage, say "Super Strength 4" and Thor's "Mjolnir" hammer, plus an added magic sword, or something, it could be beneficial to game combat dynamics.
Along that line, if "Adamantium Claws" were given an unseen "+2" then they still cut an enemy with the inferior Invulnerabilities 1 & 2, but not the highest "Invulnerability 3."
Now, this would eliminate the possibility of creating a truly indestructible and unbeatable Supervillain for combat events, but maybe that would be just as well. Rather than frustrating those players who bitterly complain against such things, a fight with an opponent so vastly superior as to be truly unbeatable could be handled through a text event, without unnecessarily elevating anyone's blood pressure.
Again, I'm just putting down some possibilities that have come to mind, as I have not yet made any decisions (and have not even seriously experimented to see how or how much I can expand the current SHUA items inventory)...