3. The main story ("Metroid", "Metroid II", "Super Metroid", "Metroid Fusion") takes place in which Planets/Stations/Clusters?
From Quiz The "Metroid" Universe [1] - Basic Planetary Info
Answer:
Zebes, SR388, Zebes, BSL
The order Samus enters these planets is Zebes, where she destroys the space pirate base, SR388, where Samus destroys the Metroid species, Zebes where she destroys the entire planet, and the Biological Space Lab (BSL), where Samus learns that executing the Metroid species, was a bad, bad idea. It seems in the main story, everywhere Samus explores explodes in some manner, in "Super Metroid" Zebes is destroyed, and in "Metroid Fusion" the BSL floats into SR388, destroying both.