Earthquake is TM26
No, Darkrai is not able to learn Earthquake.
Yes, Gallade is able to learn Earthquake through the use of the Earthquake TM.
Gastrodon does not learn Earthquake naturally, but it can learn it through use of a TM.
Aggron can learn earthquake by using the TM on it.
metang doesnt learn earthquake.
Yes, it can learn it by using the TM Earthquake
Nidoking can only learn Earthquake when you use TM26 on it.
It doesn't learn Earthquake through level up, but it can learn it through the use of the Earthquake TM.
Venusaur can only learn Earthquake through TM26 Earthquake.
Get rid of Sudowoodo
Metagross can only learn Earthquake with the use of a TM.
Nidorina cannot learn Earthquake by any method.