Question is a fair one because the top club sides with the best players from all over the world playing together week in week out would normally take a National side to the cleaners.
City would probably beat all but Spain Holland Germany and Brazil.
Barcelona would beat all National sides. Barcelona are basically Spain plus Messi.
Real Madrid v Spain would be close.
Just about everyone accepts that International football is very often a step down from top club football. Bosman ruling and TV money started the shift in power.
Would City beat England.....probably.