Thebes was , at different times , allied with Sparta when it was mutually beneficial to both . For example there was a Theban contingent , The Sacred Band , with Sparta at the Battle of Thermopylae . (Thebes effectively ended Spartan influence and prestige by defeating the Spartans at the Battle of Leuctra .)
Thebes, at the battle of Leuctra.
At one point it was Athens but they turned on Sparta.
Alliances in Greece changed. For example several times Sparta and Athens fought on the same side, at others on opposing sides. Similarly at times Sparta and Thebes fought together, at other times were opponents. Generally Sparta was allied to other Doric city-states, though again this was not a hard and fast rule. And although Persia was usually an opponent of the Greek city-states, it was Persian financial support which enabled Sparta and its allies to get a competent fleet in the Peloponnesian War and defeat Athens.
Sparta, Athens then Thebes.
Olympia, Sparta,Athens,Marathon,Mycenae,Thebes,Piraeus,or Salamis
This was Plataia, ally of Athens, at the beginning of the Peloponnesian War. It was Thebes which did the harrassing - Sparta was drawn into it when a Theban force which sneaked into Plataia was crushed and the Peloponnesian confederation it Sparta led was drawn into beseiging Plataia when Thebes demanded retaliation from its allies.
The Thebes in 371 B.C.
100
It varied over time - Argos, Sparta, Athens, Sparta, Thebes.
It changed over time - Sparta, Athens, Thebes.
Battle of Leuctra 371 BCE by Thebes.
Athens, then Thebes.
Thebes was a city-State, not a person, as well as Mycenae, Pylos, Athens, Sparta (etc.)
Megara
Peleponnesian War was a 27 year war ending with Sparta victor over Athens. War broke out when Athens sought to expand and allied with Corcyra that was a colony of Corinth. Sparta and Corinth were already allies and Sparta saw this as a military aggression. Athens at the time was lead by Pericles who refused to withdraw. Tension was high and war finally broke out when Thebes, ally of Sparta, attacked Plataea which sided with Athens.
The temporary ascendancy of Sparta, then Thebes, then Macedonia.
First Sparta, then Thebes, then Macedonia.