Actually, Snorlax doesn't naturally learn Earthquake: it has to be taught the move by TM 26.
It's at level 54. See attached link.
Nidorina cannot learn Earthquake by any method.
Rampardos can learn the move Earthquake though not by leveling up. You can teach Earthquake to Rampardos by using the TM 26 on it.
Yes Pupitar learn its.
35
Not without an a r
Snorlax Can Learn Surf - Strength - Whirlpool - Rock Smash and Rock Climb
Snorlax can learn Outrage through a Move Tutor only.
Yes, Snorlax can learn Psychic through the use of the Psychic TM. I wouldn't recommend it, though, as Snorlax has a higher attack than special attack.
a: he can only learn it by TM
Imran: Yes Snorlax can learn giga impact. When I caught the Snorlax Lvl50 that was sleeping in front of Digletts Cave it knew Giga Impact in Pokemon Heartgold and Soul Silver. I do not know about other pokemon games in which you can catch Snorlax that they would know Giga Impact or not. But of course you can teach Snorlax Giga Impact with a TM. So, yes Snorlax can learn Giga Impact.
Snorlax
Snorlax does not learn Hypnosis at all. There's no way of doing so except for cheating, not even through breeding.
Snorlax does not learn hypnosis.
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.
headbutt, drozzy, and sleep