Oh boy. I have opinions.
I find a lot of the starting Pok?mon designs are lacking in recent generations.
Generation One: A
I'm not a "genwunner," but I have been playing since Red/Blue. The sprites were awful in the original games, but the Pok?mon themselves were interesting and had solid evolutionary patterns. I particularly liked the middle evolutions for all three of the Pok?mon possibly more than the first or final evolutions. Blastoise could have stood to be Water/Ice so that each third-stage evolution was dual type. Bulbasaur was dual-type from the start, which was interesting.
Generation Two: C+
This generation tried something different, with mono-type starter Pok?mon. Okay, interesting. I think the Pokemon maintained the simple-ish designs of the first generation and the evolutions fit the base models. Chikorita is a bit bland (particularly when it just becomes taller with Bayleef) and I have never really seen the appeal of Cyndaquil, though its evolutions look a little better. I kind of wish they figured out a way to give it eyes rather than the curved lines it received. Totodile is fine, but unexceptional.
Generation Three: B-
Compared to the first two generations, this one has a few missed opportunities (in my mind). Like my thoughts on Blastoise, it is interesting that Sceptile was mono-type while Swampert and Blaziken got secondary typings. Swampert was Water/Ground which made him incredibly useless against grass Pok?mon...I feel like that could have been an interesting thing to explore. What if Blaziken was a fire/rock chicken (double weak against water) and Sceptile was Grass/Bug (double weak against fire)? Just a thought. Either way, I find these to be acceptable if underwhelming starters. Mudkip and Torchic are the first starters to have the exact same eyes.
Generation Four: A-
I feel like this is the closest we get to the first generation in terms of starter quality. Turtwig hearkens back to Bulbasaur in all of the right ways, even down to its final evolution in Torterra. Pipulp is relatively the same shape as Squirtle and has the right amount of detail. Empoleon is a great final evolution. Chimchar has a fire tail and an interesting evolutions, though the "minus" in the grade is the repeated fire/fighting final evolution.
Generation 5: D
Full disclosure: I have never played a generation 5 game, so that might tinge my thoughts on the generation. Snivy [Smugleaf?] and Servine are comically bad designs, saved only by Serperior's interesting look. Even still, it follows Chikorita and Treeko's leads as grass-only starters. So that's disappointing. Tepig is a mess and looks over-designed (my common complaint with generation five). I can't help but imagine that a Spoink fell out of bed with a Magmar and that's what came from it. I don't care for the color scheme either. Did we need another fire/fighting? It's color scheme says "Fire/Dark." Oshawott is not cute, and I don't care for it's bipedal mid-stage evolution or whatever is going on with the shell-coated final evolution. It is also mono-water, like Blastoise and Totodile.
Generation Six: C-
I feel like there are some good stages to each of these, and some bad stages to each as well. The Dungeons and Dragons vibe (tank, mage, thief) of the final evolutions never took off with me, but I appreciate seeing a few different typings, particularly since this was the first generation to give each dual type advantage over the dual type in the grass-fire-water triangle. I like Chespin well enough (though I don't understand what is "grass" about him besides his weird spiked hoodie). Quilladin is a joke, and Chesnaught is a design nightmare. Again, nothing stands out as "grass" in any of these evolutions. I actually like Fennekin's design, even if Braixen is weird furry-bait. Delphox feels close to an interesting final starter, but that is more for the fire/psychic combination than the actual look. The stick wand is dumb. Everyone loves Greninja, but Froakie looks like a mess, though it fits its proportions a little better with Frogadier. Greninja is a bit over-designed, but I don't actually hate it (despite its oversaturation on the battle scene).
Generation Seven: B
Litten and its mid-stage look great. I don't even hate Incineroar, and am glad we missed another fire/fighting type. I like Popplio's look and don't dislike the middle stage, though I think Primarina is weirdly over the top. Rowlet might be a little boring, but I think it hearkens back to earlier generations. Dartrix is okay besides
the 90s hairstyle and Decidueye is a busy final evolution, but a neat concept. I wish they could have done a little more with the second wheel (Dark-Fairy-Ghost) but it's all good there.
Generation Eight (First Evolutions Only): B-
We're going to get another fire/fighting for sure. Grookey looks fine enough but we're probably going to get another "Pokemon holding a stick" final evolution. Sobble seems out of place. I feel like a lot of starter Pok?mon lacked distinct personalities so the trainer could assign the personality to it through gameplay. But a crying amphibian? What happens when you get one with a bold or brave nature?