Actually, Snorlax doesn't naturally learn Earthquake: it has to be taught the move by TM 26.
Rampardos can learn the move Earthquake though not by leveling up. You can teach Earthquake to Rampardos by using the TM 26 on it.
Numel does not naturally learn Earthquake in its movepool. However, it can learn Earthquake through TM26 in Pokémon games, starting from Generation III.
Pupitar can learn Earthquake at level 50. Alternatively, it can also learn Earthquake through TM26 in some Pokémon games.
No, Mewtwo cannot learn Earthquake. It is a Psychic-type legendary Pokémon and Earthquake is a Ground-type move, which is not compatible with Mewtwo's movepool.
No, you'll have to use the TM on it. You can find that in victory road.
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.
Gastrodon does not learn Earthquake naturally, but it can learn it through use of a TM.
Yes, Gallade is able to learn Earthquake through the use of the Earthquake TM.
Aggron can learn earthquake by using the TM on it.