I'm not sure but I think Tyranitar learns Earthquake after evolution.
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It doesn't learn Earthquake through level up, but it can learn it through the use of the Earthquake TM.
Aggron can learn earthquake by using the TM on it.
Grotle is not able to learn the move Earthquake by leveling or by TMs. It's evolved form Torterra is able to learn Earthquake at level 32.
Level 54 :D
Sorry, Bastiodon doesn't naturally learn Earthquake. But, you can teach it TM 26, Earthquake.