It Learn Hypnosis At Level 16 Must Catch Level 16
Haunter should know Hypnosis already when it's caught.
the only way haunter can learn hypnosis is to have two in daycare and it breed gastly the lvl1 gastly should know hypnosis hope i helped :)
If you caught it as Haunter it will start with it. Same as Gastly
Do you mean "Haunter"? Haunter should already know Hypnosis. If it doesn't, use a Heart Scale. This is not a wise comment, this is the answer.
There is no TM for Hypnosis in any of the versions of the game. Unfortunately, the only way to learn hypnosis is through breeding or your Pokemon leveling up. Level up haunter and it might get hypnosis.
Technically, Gastly had Hypnosis at level 1 and by the time you catch it the move has been overwritten by moves Gastly learns at higher levels . So, you need to obtain a Heart Scale in the underground and take it to someone in Pastoria City, who will then be able to teach Haunter Hypnosis.
Slowpoke doesn't learn hypnosis
Wobbuffet cannot learn Hypnosis.
Snorlax does not learn hypnosis.
Yanmega cannot learn Hynosis. However, Yanma can learn Hypnosis at level 38.
Gengar knows hypnosis at level 0.