How many Golden Enemies are there?

Solution 1:

This video has the location of all of the golden machine lifeforms:

In order, they are:

• Golden Goliath Biped (City Ruins)
• Golden Stubby (Flooded City)
• Golden Goliath Tank (Desert - Apartment Complex)

This video also has the same three golden enemies.

As you progress, these enemies tell a story of revenge for killing their brethren, which I believe 9S comments on, questioning the motivation behind the concept of revenge, which the Pod describes as an old human behavior.

Unrelated to these golden enemies, there is also the Golden Bunny Statue in the Amusement Park, which is extremely useful for leveling up from around 60 to 99.