Gondolin vs Numenor

[de Sosa]

Both cities, in their prime, face off in war.

Which kingdom wins?

[Randy Mandy]

Numenor is a kingdom, not a single city.

Gondolin is also a kingdom, but it does have one single city.

Numenor would have a hard time attacking Gondolin, because of its location in the center of a ring of mountains.

Gondolin absolutely cannot attack Numenor, because of its location in the center of a ocean and its lack of a navy.

Ten thousand soldiers were a major commitment for Turgon.

Six thousand soldiers were a pittance for Gondor in the days of its glory. And Gondor wasn't nearly as fearsome as Numenor was.

tl,dr: Numenor beats Gondolin. Not swiftly or without getting a bloody nose, but it essentially cannot lose.

[Sharpandpointies]

Pretty much. Gondolin is vastly outnumbered by the forces brought to bear against it.