Agreed with Pendaran on the Wonder Woman/Superman point.
Wondy's compartmentalised durability is product of her durability stat, for lack of a better term, so Superman's durability stat in a composite would raise said stat to that "weakness" no longer exists.
Gladiator's radiation weakness would be more analogous with Superman's weakness to kryptonite (in fact it is a pastiche of it).
My gut feeling would be that, to remove Gladiator's weakness, I think you'd need to add in someone who is actively empowered by radiation or similar energy absorbing powerset. That would be, in my mind, the appropriate rather than just assuming that an absence of weakness equates to removing a specific weakness.