Advantages :
Sparta : strong land army; women could own property; women had freedom; powerful; strength/training
Athens : freedom; strong navy; strong economy; trade; industry and jobs; larger population; wealthy
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Disadvantages :
Sparta : Surrounded by hostile city-states; landlocked; harsh military training; lived in fear of a revolution; violet city; no democracy
Athens : Women could not participate in government; land army not as good; women could not participate in government; women had no freedom
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Allies :
Spartan Allies : Elis, Tegea, Corinth, and other states
Athenian Allies : The Persian king.
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Effects of the Peloponnesian War:
The Peloponnesian War marked the end of the Golden Age of Greece, a change in styles of warfare, and the fall of Athens, once the strongest city-state in Greece. The balance in power in Greece was shifted when Athens was absorbed into the Spartan Empire.
(I dont know about their key victories though, sorry)