Worst Starter Per Stage

Stage 1: Tepig (a stain on an otherwise wonderful gen, Oshawott is so much better)
Stage 2: Dartrix (I'm not a fan of the Rowlet line in general aside from Rowlet itself, but this is the worst one in the line)
Stage 3: Emboar (This thing is hideous, it looks like an obese hog in a girdle, and the shiny is even worse)

Stage 1: Popplio (It looks weird with those ears)
Stage 2: Brionne (Hideous, looks even worse than Popplio)
Stage 3: Emboar (Shouldn't have become Fire/Fighting)

Stage one: Chikorita - Bad
Stage two: Bayleef - Also bad
Stage C: Meganium - Less bad, but still disappointing in battle and a pure Grass final stage

Going mostly by design wise here.

1 - Chimchar. Not a fan of it and its butt-fire aspect.
2 - Quilladin. While I am fine with its evolution it really is the ugly ducking of the middle stages to me. Looks all kinds of awkward and I think it's the one starter I am really struggling to recall the name of.
3 - Emboar. Was rather disappointing to me, and not just because it was another fire fighting starter (third in a row). Meh design to me, underwhelming stats, etc.

1-Chikorita. Just don't like it. At all.
2-Servine. It's just Snivy but a little longer. So lazy.
3-Chesnaught. They had something really good with Quilladin, but it just ended up like it was trying to cosplay Torterra. Badly.

Stage 1 - Fennekin. To be fair I don't think there are any 'bad' first starter evos - I just like Fennekin the least out of all the starters.
Stage 2 - Quilladin. It just looks awful, and feels the most like a place holder for the final evolution than any other mid stage starter pokemon.
Stage 3 - Incineroar. I feel like it wasted the potential of its previous evolutions and looks incredibly goofy.

Stage 1: Popplio. One of the Galar Pokemon might be my eventual pick, but I want to let them grow on me first.
Stage 2: Grotle. Not awful, but it looks more like an armadillo than a tortoise.
Stage 3: Delphox. It just looks like a goofier version of Braixen, and I just can't take it seriously.

Stage 1: Chikorita. It looks...really off-putting.
Stage 2: Quilladin. Air Man-type body designs were never really my thing. Special mention goes to Pignite.
Stage 3: Charizard. I just have my personal vendettas against it, really.

Stage 1: Kind of a difficult one, but Tepig takes the cake. I still like it though.
Stage 2: Prinplup is the pinnacle of awkwardness.
Stage 3: Charizard, never really liked how it got so much more love than the other 2 Kanto starters.

Stage 1: Chikorita (Don't really dislike it, but it's my least favorite in comparison to others.)
Stage 2: Quilladin (It feels lacking, design-wise.)
Stage 3: Emboar (I didn't like the line altogether, and it's the one fire starter that I dislike from start to finish.)

I don't know about stage 1 and stage 3, but my least favourite stage 2 is indefinitely Brionne. Okay, I used to like this, until Primarina was revealed and I realised how much better it looked than the middle form. I mean, what is better, a badass mermaid or some fat educational game mascot reject? Yeah that's what I thought.

Stage 1: Mudkip or Chespin (I'm really not too opinionated here, these just don't appeal to me)
Stage 2: Dewott (Oshawott is fine, and Samurott is awesome... But Dewott is just lame, for lack of a better term)
Stage 3: Incineroar (Incineroar needs to go back to whatever cheesy 80s humanoid animal action cartoon it came from and stay there forever)

Stage 1-- Chimchar. I don't like that his rump is on fire and thought his story in the anime with Paul was such a rip-off of Charmander. Chimchar's grin and those gleaming eyes were cloying to me as well, and this is the stage of his line I can tolerate best. It just keeps going downhill as he evolves. I cannot see the appeal of this line beyond competitive useage.

Stage 2- Pignite. Bad cry and just not an attractive design, the wrestling suit is too literal-looking. I also would have liked him to remain quadruped-- Tepig was cute. Especially since this is the third fire/fighting starter in a row why not change up the formula? Make this one less anthropomorphic and more like a warthog with both hooves firmly planted on the ground?

Stage 3-- Incineroar. I was all for Team Litten, until I saw Tony the Tiger here. I was shocked and disappointed. I thought he was going to keep a lithe design worthy of a cat, not this hulking barrel-chested wrestler. Unlike Tepig nothing in Litten's previous evolutions prepared me for the direction this line was going in. This just looked tacked on out of nowhere.

Stage 1: Tepig - Tepig has grown on me over the years, so much so that I find it quite endearing. However, when I initially glanced at this pig-inspired pokemon, I was disappointed. By no means do I dislike this pokemon, I'm actually quite fond of it, but I would say that it among my least favourite out of all of the pre-evolved starters.

Stage 2: Wartortle - I've always thought that Wartortle simply has a rather odd resign. It's a slightly larger version of Squirtle with elf ears and a tail. It's a tad plain and lacks the creative designe that later starters have. Also, those ears just look out of place on a turtle. Quilladin is a very close second, I've always felt that it's just an awkward looking pokemon.

Stage 3: Venasaur - I LOVE Bulbasaur and Ivysaur so much, however, I have different feelings about Venasaur. It's just a fatter, less adorable version of Ivysaur. I don't dislike Venasaur by any means, I do like it, just a lot less than other fully-evolved starter pokemon. Again, it lacks a creative design. Embroar and Incineroar are second and third place respectively, as both pokemon fail to stand out to me. It's like they're attempting to be Infernape and Blaziken although they fall flat. The bipedal, aggressive looking, hypermasculine fire starter design is overdone.

Stage 1: Oshawott - I don't think there's any starter basic form I actually dislike, but Oshawott is the ugliest of the lot in my opinion. To me, it kind of looks like a weird cross between Bidoof, a snowman and Piplup. I'm glad Dewott looks so much better.

Stage 2: Quilladin - This one was difficult to choose. Croconaw is ugly and ignores most of the likeable features of its predecessor's design, Combusken looks very odd next to Torchic and Blaziken, and Servine is just a bigger Snivy. All 3 of the Sinnoh starters mid-stages look like they're going through their awkward middle school phase too. Despite all of this, the award has to ultimately go to Quilladin for being absolutely hideous.

Stage 3: Sceptile - Again, there's a lot of final forms I'm not a fan of. Venusaur is just an uglier, fatter Ivysaur. Samurott is a huge design leap which makes no sense to me. I remember picking Piplup as a kid and being absolutely devastated when it evolved into Empoleon, as it was by far the least cool of the final evolutions in that generation to me, but it's grown on me since. Chesnaught seems to be super divisive, and I'm on the side of not liking it, but I don't think it's completely awful either. I'm not a huge fan of Dartrix becoming a ghost type upon evolution, but I don't dislike Decidueye's design. But with that all out of the way, the worst offenders of bad final evolution design are the gen 3 starters. Blaziken suffers from the same problem as Samurott, in my opinion. Swampert is just a big ugly Marshtomp, which is sad because I LOVE Mudkip and Marshtomp. And the worst of the lot is Sceptile. I don't know, he looks ugly and super smug. Just overall has a very punchable face.