Ay, I know this has been answered, but I want to give a bit of a breakdown comparing Hypno to other Psychic types.
Starting things off, Hypno doesn’t really have the offensive presence that is usually preferred in game. It’s stats are pretty balanced, and it has pretty good Special Defense. While this is good in some cases, like I always say, it’s better to be fast and hit hard than to be bulky when you’re doing a playthrough.
Now, I have a few suggestions that do pretty well in game. First is Espeon. Eevee is a gift from Bill in Goldenrod City, and to evolve it into Espeon, max out it’s friendship and level it up in the daytime. Espeon is great for in game usage due to its high speed and Special Attack, plus it has good Special Defense. I’d teach it Psychic, Bite, Morning Sun, and Attract because it’s movepool is garbage.
Next is Alakazam. It definitely has a better movepool than Espeon. It’s Speed and Special Attack are superior to Espeon’s, and its Special Defense is tied with Espeon. It’s downside is that it’s Defense and HP are worse that Espeon’s, so Espeon can, overall, take hits better than Alakazam. The moveset I would use would be Psychic, Recover, Fire Punch/Ice Punch, and Thunder Punch/Ice Punch. It gets earlier recovery at an earlier level than Espeon, which is nice. You could use Thief over one of the elemental punches for Ghost types.
Now I’ll give a breakdown of Hypno. It has better Defensive stats than Alakazam and Espeon across the board, but it’s offensive stats are very lackluster compared to Espeon and Alakazam’s. It can take special hits well, I guess I’ll give it that. I would use a similar set to the Alakazam one, Ice Punch, Thunder Punch, Shadow Ball, Psychic, since it provides great coverage in BoltBeam.
So, hopefully I got all of this right, I’m not very familiar with earlier Pokémon generations. I know it was before the physical/special split though.... so yep.
Hope this helps! :)