I know most Psychic types can learn it, but any specifics? My memory is a bit foggy

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Watchog

5120891 Hypno, Drowzee, Kadabra, Alakazam, Gengar(I think) Darkrai(I know he has Dark Void but still) and I'm not sure about others

5120891 I know Crobat can.

5120891 Ponyta can learn it by egg through chain breeding (the easiest way is by having a male Smeargle Sketch it, breed the Smeargle with a Psyduck/Golduck until you produce a male Psyduck, then breed that with a Ponyta/Rapidash).

Hoothoot can and so can bronzor.

Noctowl

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http://bulbapedia.bulbagarden.net/wiki/Hypnosis_(move)