You'll need to evolve Drowzee to get Hypno.
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Yes, Pokémon in Crystal can learn Headbutt through level up and they are Slowpoke as well as its evolution of Slowbro, Hypno and its pre-evolution of Drowzee, Cubone and its evoluton of Marowak, Snorlax and Slowking.
Drowzee evolves into Hypno at level 26.
Drowzee and Hypno are top choices. but most psychic Pokemon know/can learn Hypnosis.
In Pokemon Crystal.
you cant you have to find a Pokemon like hypno ,or a butterfree has sleep powder