Fantastic post, you are very informed (and funny too, Sabrina laughs in haiku got a laugh).I love these types of lists. If you don't mind, I'll chime in with a little.
Hitmonchan has a case for E-tier and possibly the worst Pokemon in the game.
You of course get Hitmonchan at a decent level for the location, level 30 isn't bad for potentially right after Rock Tunnel, plus having a nice 105 base attack paired with 76 base speed means it should hit hard and outspeed some of the game along with how early it is compared to some others. It does hit hard if everything goes in its favor, but that rarely happens with the boss battles in the game. Plus in the latter half of the game, trainer battles pack a Pokemon that usually has a special move, which if relying on accuracy of Mega Punch, leaves a person running to heal a lot. Once Strength is available, use that, unless of course, you have Body Slam for it.
The normal trainers can be won over by using the Mega Punch TM, the Strength HM or if possible, the Body Slam TM (Which isn't a hard thing for most Pokemon in this game...). It is the boss fights where this mon has little to any use besides fodder. Though of note, most routes after Koga can pretty easily kill it, gotta love that 35 base special mixed with a bad health stat.
Erika packs two grass/poison types that can easily kill it with their special moves in two turns, while you might be able to kill them in two turns if you are 5 or 6 levels higher. Koga will just annoy you with Smokescreen on the two Koffings while potentially killing it, Muk sets up and ignores its very existence, and Weezing has fun (this actually depends on a lot factors, mostly your patience or the AI killing itself and you.). Sabrina laughs in haiku. Blaine will more than likely burn it alive, but can go in your favor if Fire Blast pulls a miss, that's if you get past the Rapidash. Giovanni, actually has a even matchup until Hitmonchan has to tap out.
Lorelei loses Dewgong due to it spamming Rest. (might be able to kill Cloyster with some luck.). Bruno will lose his Onix(s) if he doesn't Harden his rock snakes, while everything else kicks the crap out of Hitmonchan. Yes, even another Hitmonchan will kill it, mostly due to Counter, though Thunder Punch/Fire Punch will do the same damage your Hitmonchans Strength will do if 5 levels lower, just as a note. Agatha laughs in Braille. Lance doesn't care about it (though it will kill the Dragonite due to it spamming Agility) . The Rival has one Pokemon that might not have a good time, that being the Rhydon.
With other Pokemon, you can usually think of some weird gimmick to use it for, but Hitmonchan has nothing besides its god awful sprite. I can honestly think of weird crap to do with Tangela, Parasect, and even Ditto, but Hitmonchan is ridiculous in the fact of how much it sucks. Medium Fast exp can't save it.
Drowzee has a case for A-tier and has some uses that are pretty nice.
Drowzee is a lot like Magikarp in this game, it starts off pretty weak, then powers up to pretty high heights as you go through the game. Catching it at Route 11 means the lowest level it can be is Level 9, which sucks for that point in the game. This is the only big negative, which it happens to share with Magikarp too. Drowzee will have to wait till Level 17 for Confusion, which isn't that bad due to Route 11 and the S.S Anne holding 20+ trainers to farm. Evolution at Level 26 is early enough to dumpster the mid game, while being a fantastic mon for the late game. Psychic at level 37 is pretty nice as well, along with a decent attack for the normal moves it can learn.
Hypno is a Psychic Pokemon with a decent attack, very few route trainers will cause trouble for it.
Against Surge as a Drowzee is fine until the Raichu, it is pretty much a for sure defeat unless hypnosis works. Erika will trade blows with you if you just evolved and didn't use the Psychic TM on it. Koga cries in sign language. Sabrina is actually easy due to access to a physical move and her Alakazam only having Psybeam, so you can just Psychic spam after she puts up a reflect to eventually lower her special. Blaine is pretty even overall, besides that Fire Spin problem. Giovanni loses while scoring some hits.
Lorelei is the biggest problem in the Elite Four, mostly due to freeze. Bruno dies. Agatha has that confusion hax, but otherwise it good for Hypno. Lance is kind of neutral, but with the level difference (most likely), it is in Lances favor. The Rival loses half of his team, though you can't really beat his Alakazam without Hypnosis.
This leads me into why I really think Drowzee should be A-tier. Hypnosis allows it to skate by where it struggles. It has a lot of winning match ups, but also some losing ones, which would normally put it in B-tier. The ability it has to bully a sleeping Pokemon is something that is super powerful, especially considering the defenses of Hypno. There are very few things that could one shot Hypno, allowing it to beat stuff down, or put them to sleep. An example is that both Lance's Dragonite and the Rival's Charizard/Blatoise/Venusaur can't one shot it (unless a crit), when Hypno is 12 levels lower than Lance and 15 levels lower than the Rival.
Honestly if Sandslash, a pokemon with similar problems, but no utility can sit in A-tier, so should Hypno.
I think I'll stop there, see if I'm overstepping or something before continuing.
Using Hypno atm in my Charmander run. It’s definitely A, but I haven’t been using Hypnosis a ton because accuracy. That said Sleep in RBY is silly. I had Hypno for Surge - I can confirm he does like nothing to it. Even with Confusion it just 2HKOs everything and outbulks all the weak attacks the game throws at it. The only thing being annoying is the initial grind but you can get a level 13 one to mitigate this IIRC.
Please post more, this was a great start!