Because I have so much to do and because this subject is well-known, and the Wikipedia page well written, rather than re-invent the wheel I'm quoting here from Wikipedia's "Planets in astrology". When I have more time I'll fill in the corresponding archetypes and equivalences with other symbolic and psycho-c\socio-spiritual systems of thought.
To most modern Western astrologers, Pluto is the ruling planet of Scorpio. In Roman mythology Pluto is the god of the underworld and of wealth, hence the coin-and-chalice glyph. Pluto and its moon Charon form a unique pairing in the solar system because Charon is so massive relative to Pluto. This means that they revolve in a 'dumbbell' formation around a common point in space lying between them, permanently locked in a 'power struggle' for dominance. This is symbolic of the role Pluto has come to represent astrologically. Pluto takes 248 years to orbit the sun, spending on average approximately 21 years (20.6) in each sign of the zodiac. However, Pluto's orbit is so eccentric that this can vary dramatically, from 25 years in Cancer (1913 - 1938) to a mere 12 years in Scorpio (1983 - 1995), when its orbit was actually closer to the sun than Neptune's.
Astrologically Pluto is called "the great renewer", and is considered to represent the part of a person that destroys in order to renew, through bringing buried, but intense, needs and drives to the surface and expressing them, even at the expense of the existing order. A commonly used keyword for Pluto is "transformation". It is associated with power and personal mastery and the need to co-operate and share with another, if each is not to be destroyed. Pluto governs big business and wealth, mining, surgery and detective work, and any enterprise which involves digging under the surface to bring the truth to light. Pluto is also associated with the day Tuesday along with Mars.
Pluto is also associated with extreme power and corruption; the discovery of Pluto in 1930 coincided with the rise of fascism and Stalinism in Europe, leading to the Second World War. It also coincided with the Great Depression and the major proliferation of organized crime in the United States.
Its entry into Cancer in 1913, the sign in which it was later discovered, coincided with the First World War. It is also associated with nuclear armament, which had its genesis in the research of the 1930s and 40's. Later on, it gave rise to the polarized nuclear stand off of the Cold War, with the mass consumer societies of the United States and other democracies facing the totalitarian state socialism of the USSR. The discovery of Pluto also occurred just after the birth of modern psycho-analysis, when Freud and Jung began to explore the depths of the unconscious. In real life events and culture, Pluto has been a major astrological aspect.
In art, movements like Cubism and Surrealism began to deconstruct the 'normal' view of the world and reassemble it in new and sometimes disturbing ways. In medicine Pluto seems to be associated with regenerative forces in the body involving cell formation and the reproductive system. Pluto is considered by modern astrologers to be co-ruler of the 8th house with Mars. Many traditional astrologers do not use Pluto as a ruling planet, but do use the planet for interpretation and predictive work, obliquely making reference to projections of influences from higher to lower dimensional spaces.
Comments: to be added...