Kangaskhan>Hypno: Unlike Hypno, Kangaskhan has no switchins and outspeeds all the slow mons. It also has useful defensive utility since all the Grounds, especially Nidoking, do not like this mon. Most of the fastmons are physical attackers too, so the opponent often times just is forced to trade 65% of their Lapras for your Kang. Hypno is actually semi-exploitable, as a lead you obviously get slept, but in the back Slowbro and to a lesser extent Rest Hypno can farm you. In general I think fastmon == good, so Kang is better.
Haunter: Not a big fan of this mon. Hypno is everywhere and mons like Dodrio, Dugtrio, Kadabra, and Moltres are independently good. You get the fast Hypnosis and drop on Kang but I wouldn't hang your hat on that, it is really inconsistent for my tastes. I think sleep in general is worth a lot less since Hypno is really good already, and Lapras can also get sleep on switches.
Victreebel: Secretly goated? Immense role compression of sleeper + Jolteon check, and Razor Leaf is a surprisingly decent STAB to click since fliers and fires aren't on literally every team. The tier seems to be centralized around Normals, Psychics, Lapras, and Grounds, none of which resist. The 10 less speed of Venusaur doesn't really matter and getting Stun Spore is worth way more.
Golem: Rather mid. Running Hypno + Lapras in the back eats up a lot of your slots for speed, and running 3 mons in the back that can't revenge anything is bad in my opinion. Nidoking for the most does what Golem does, it has the better speed tier and doesn't sacrifice too much. I'd say the advantage to Golem is that it walls Dodo but if someone is loading Dodrio they probably have some plan lined up for it, Earthquake hits mons hard but since Golem is slower than everything and gets OHKOd by a bunch of stuff, switching something into EQ and threatening sleep or whatever is surprisingly decent. I'm also a believer in Tangela too.
Slowbro: I don't think this mon is particularly good. The main reason is how are you building with this, you probably are running Lapras + Hypno, and running two slow waters really incentivizes you to use a real Jolteon check (not Dugtrio) which puts a Ground on your team. This probably gets owned by Victreebel, 4 mons are slower. Speed is king in lower tiers, even when there is bulk. Still, you really need to respect Slowbro in the builder even though I don't like using it.
Ninetales and Moltres: Really nothing likes switching into Fire Blast, Ninetales is a bit better do the speed tier and being better into Haunter, but Moltres gets Agility. I still think outspeeding Kang is more important, however.
Jolteon: Maybe the tier is just overprepared for this mon, but I've never really seen Jolteon do much. Grounds are everywhere, it's rather frail so it doesn't want to just switch into attacks, even if you don't run into Grounds, Grasses or Thunder Wave users really hurt you and fitting Agility is difficult. However, like Slowbro, it has a seismic effect on teambuilding which forces a ground on most teams. I dislike this to be honest because it creates a matching problem that makes matchups more one-sided, Grounds are rather meh into not-Jolteon so you'd like to drop them into not-Jolteon, but you need to run them to stop Jolteon, but you also need to run Jolteon so the opponent runs Grounds, etc.
Gyarados: Despite everything, this mon has genuine advantages that nothing else in the tier really has. Fire-types are the realest they've ever been, since Lapras, Normals, Grounds, and Psychics don't really like switching in. Furthermore, Water-type attacks are rather threatening if you can get around Lapras and Slowbro. Hydro Pump gets the 2HKO on normals, Grounds are everywhere, Fires are real, and Thunderbolt prevents Slowbro and Lapras from just switching in and going infinite. It also is a great Dugtrio check. Genuinely decent mon.
Tangela: You'd think this mon does literally nothing because Hypno exists, but owning Golem and Dugtrio is still useful. It's neutral typing also makes it ok at clicking Stun Spore vs so much of the tier, too. Lastly, like Victreebel, it checks electrics even better actually, since it isn't weak to Pin Missile / Psychic and has better physical bulk.
Articuno: Not a big fan of this mon. On paper this mon goes stupid since Lapras doesn't usually last long in a game, but I've seen this mon whiff so many times. I really don't know why, either.
Electabuzz and Raichu: Worse Jolteons that have ways to get past grounds, Electabuzz is a bit higher since I think Psychic is worth a bit more than Surf + Agility.
Raticate: This mon registers a 9 on the shitter scale but it's somehow usable. It outspeeds all the lead sleepers and has Super Fang. Chunking whatever for 50% is just really good, you can do stupid stuff like Super Fang Lapras into Hyper Beam and trade with all the slower bulky mons, unlike the faster and stronger attackers like Dodo, Dug, and Cat.
Dragonite: Similar advantages to Gyarados but I think the upsides aren't as high. Thunder Wave is good but slower mons are usually going to stop you anyways, and I think the weakness to Blizzard is more detrimental than the weakness to Blizzard (Gyara can eat a non-STAB Thunderbolt vs Lapras). I think that the Water STAB is worth much more, too. Still usable, though, it has Thunder Wave and Agility sets.
Clefable: Soured on this mon a ton. Hypno outclasses this mon mostly and running both makes your team really really slow, and Clefable doesn't have the polarized matchups to get entry like Grasses or Grounds to really make it worthwhile.
Venomoth: I think this mon is rather meh, epic you get to outspeed most of the other leads (except Haunter) but like what do you do afterwards. Grasses have more utility + aren't forever walled by Hypno. Usable in getting the jump on grass leads but rather niche in the sense that the mon is really meh outside of that.
Venusaur: Sadly I think this mon is 100% outclassed by Victreebel. The extra speed doesn't really get you any extra targets + you 100% have to switch out afterwards because so many mons switch in for free without the fear of Stun Spore. Like Venomoth, you can use this to get the jump on lead Victreebel while still having a semi-functional Grass afterwards.
Nidoqueen: You live a lot more often with Nidoqueen but since everyone is using Nidoking I think the speed drop is way too important to give up since you lose the mirror. Probably worth using versus people who don't load Nidoking.