More Discussion Needed:
Lotad S --> A (I will make an argument for this thing to stay S when I have time. I'm definitely confident in this one instead of Corphish where I was confident then realised I wasn't.)
Zubat B --> A
Oddish (Vileplume) C --> B
Groudon A --> S
Kyogre A --> S (I don't like the legends being in S because they are so late, but I'll look into it more and post my thoughts then)
Latias S --> A
Latios S --> A
Swablu C --> B (I am going to use a Swablu, so I'll post my thoughts on this in a couple weeks when I finish the game. I'd still like discussion on Swablu now though)
Tropius A --> B
Geodude (No Trade) A --> B (was this for Geodude (Trade) as well or not? I can't really tell)
Magikarp A --> S
Tentacool B --> A (maybe? It's a possible shift for sure)
Ralts (Gardevoir) S --> A (I obviously disagree lol)
Ok, time to take this list on...
Is the Water Stone still very late? If so, I think that Lombre might end up lagging a little too much mid-game, so A-Tier might end up being the better place for it, which was pretty much the consensus anyway. However it is still very powerful, and will be in the higher ranks of A-Tier for sure.
Zubat could realistically be A-Tier.
Availability: Early -- Granite Cave. This is after the 1st badge, but Roxanne would have wrecked Zubat if it was in Rusturf Tunnel so it's just as well.
Typing: Poison/Flying. Obviously Flying-Type is good to see on an in-game tier list thanks to HM: Fly, though the Poison-Type isn't anything special in Hoenn. Neither is Flying-Type, really.
Stats: Pretty decent. Zubat is very fast, which is something Golbat and Crobat definitely build upon. Golbat's attack is great and Crobat's is awesome, while they both also have usable special attack stats. Their bulk leaves some to be desired, though.
Movepool: Pretty good. It has a good TM movepool with moves like Sludge Bomb and Shadow Ball, while its level-up movepool gives it useful STABs all the time. Most notably, it gets Wing Attack at level 13, in time for Brawly.
Major Battles: It destroys Brawly, quad-resisting his Fighting-Type attacks and sweeping him with Wing Attack. Not so good against Wattson, and from there it's more "usable but nothing special" in the major battles, excluding Tate & Liza, which destroys the poor bat. However, depending on where the move tutors are, it might have Giga Drain for Wallace. Steven also resists most of Zubat's attacks. However, Crobat's speed and strength means that even neutral attacks do a huge chunk, keeping it consistently useful throughout your adventure.
Other: Golbat --> Crobat is a friendliness evolution, meaning that your experience with Zubat may change depending on how well you treat it. I'm sort of undecided between B- and A-Tier right now, but I'm leaning B.
Oddish (Vileplume) all depends on where the Leaf Stone is. Anyone have any info on this?
The Hoenn legends just come too late to be considered S-Tier imo (by that I mean Groudon and Kyogre).
I agree with keeping Lati@s in S-Rank. They can be a little underwhelming at times, but that's just because you have such huge expectations from the twins because they are legendaries. They would look way too out of place in A-Tier.
I personally agree with Swablu in B-Tier, but IDK, I don't have any experience with it in any game besides Colo + XD and it obviously has things like megas now to boost it ever higher.
Tropius to B looks good.
Geodude (No Trade) in A still works for me. Don't forget that Graveler can use Eviolite, which boosts its bulk substantially and means that the difference between it and it's final form isn't so noticeable in-game. It also has decent attack power either way.
I think we can all agree to Magikarp in S lol.
I think Tentacool in B, but more discussion is definitely needed.
Also I'm going to go ahead and move Ralts (Gardevoir) down. I'm still a bit undecided on the matter, but as a community I think we've put it in A lol.
The conclusion we reached with Shroomish was A-Tier, so I'm going to put it there. It can obviously be changed at any point, though.
And finally, IAR just posted about Lileep, which I can't see anyone really having a counter-argument for, so I'll move it down too.
Changes Since Last Time:
Shroomish Untested --> A
Magikarp A --> S
Ralts (Gardevoir) S --> A
Tropius A --> B
Lileep B --> C (though it could actually be D lol)
More Discussion Needed:
Tentacool B --> A
Zubat B --> A
Lotad S --> A
Oddish (Vileplume) C --> B
Swablu C --> B
Carvanha S --> A (It should be 100% S imo)
Feebas C --> D
Zigzagoon A --> B
Electrike A --> S (I was a little premature on this tbh)
Rhyhorn C --> B (This comes right when all of the water starts, which really hurts it. I think C, but it's at least worth some consideration)
Horsea (Trade) B --> C
I think that's all of them. There was a bit of discussion about Numel, but people were arguing about S, A and B, where both times the consensus was A. I'm not saying he can't change in the future, there just wasn't a proper nomination at any point.
Also, though I don't like doing this,
Treecko will not change tiers. A-Rank is where it belongs, and unless something substantial happens like a patch giving Treecko Leaf Storm at level 6, Treecko WILL be A-Tier. It has completely dominated discussion in this thread thus far, so I think we should move on.