In Pokémon games, grass starters usually feel like the third option. It takes a certain type of person, more thoughtful and tactical, to appreciate the quiet but capable grass-type starters. Grass Pokémon starters have a very diverse line up over the generations of games but some are certainly better than others.
While it might not be fair to rank them up against the water and fire starters, it is certainly fair game to compare them against each other. Grass starters typically receive a bad rap and get dismissed as third options but there are several starters ranked high on this list that rival their aquatic and fiery peers. As a note, since Pokémon Sword and Pokémon Shield have not yet released, Grookey will remain unranked in this list.
From the Kalos region, Chespin wins the worst spot on this list for several reasons. Described as the "spiny nut" Pokémon, Chespin is closest to a mole type creature, although a butchered version of that. The mid-level evolution Quilladin is just a round version of Chespin and the final evolution of Chesnaught is a large white dinosaur-mole creature that bears little resemblance to the previous two versions.
Chesnaught also has fighting as its secondary type, which needs to be shelved as a secondary type for several generations before it gets used again. It's the weakest choice between the three Kalos starters, primarily due to its unappealing final form. Chesnaught having the large round shell form seen in many other grass starters' final evolution is shoehorned in because the base form doesn't dictate it.
Snivy might be one of the few cases of snakes not being cool. The Unova region is home to three incredibly weak starting Pokémon, including the grass snake Snivy. Over the course of its evolutions, Snivy loses its legs and gains a slightly longer body and some gold accents to create a regal snake in Serperior. No secondary type, nothing extra special besides being a large snake.
Despite starting in a place where something interesting could have happened, like a snake with legs, it just results in a glorified garden snake. How did Game Freak manage to mess up a snake? Snakes are naturally a cool animal and they have made several well-designed snakes in the past but somehow the most prominent snake Pokémon is easily the lamest in design and execution. Snivy has one of the most uninteresting evolution lines in all of the Pokémon starters.
While Treecko is a great starter, it doesn't get to be higher on the list because it has some strong competition. In the Hoenn region, Treecko doesn't stack up against Mudkip and Torchic since they bought have secondary types in their final evolution while Sceptile does not, excluding the mega evolution because that's a very specific case.
Treecko goes from a very woodland Gecko to a very large woodland Gecko? It's unclear and not very exciting to see. On face value, Treecko seems like it deserves better but when you break it down, Treecko just can't keep up with some of the other grass starters in this list.
The Johto region has a strong case for being the GOAT region, in close contention with the Kanto region. That said, like most grass starters, Chikorita is a strong number 3 out of the Johto starters. That's not to say Chikorita isn't great in its own right, but Totodile and Cyndaquil are better options.
The Chikorita evolution line also gets bonus points for having a very original design that does not have an animal to be based on. A dinosaur is the closest comparison to Meganium, but that's about it. Meganium also does a good job of embracing the beauty and elegance of nature without relying heavily on being a large tank with a shell, like many of the other grass starters have.
Tortoises are some really interesting animals, making Turtwig a really interesting Grass starter. Turtwig and the final evolution of Torterra embody grass and earth in their design. Torterra feels like it truly came from the Earth and gives off the embodiment of power. Turtwig and its evolution line go into the power of Earth and nature as opposed to beauty.
Turtwig itself is also tied with Piplup for being the best starter in the Sinnoh region, beating Chimchar easily. The entire Turtwig evolution line has great designs, even the mid-level evolution, Grotle, is designed in a way that is a believable step between the two forms, without either feeling too far of a jump.
The original Grass starter from the Kanto region Bulbasaur might be number 3 in Kanto, but he is number 2 on the list of grass starters. Bulbasaur is one of the best, being the cabbage toad that it is. Not only is Venusaur, the final evolution of Bulbasaur, the game mascot for both Pokémon Green and Pokémon LeafGreen but it is also on the most intimidating and strongest grass Pokémon around.
In addition to grass, Venusaur also rocks the poison type as one of the few early starters with a double type. Ivysaur is also a great mid-level design, proving a reasonable and convincing step between the first and final forms of Bulbasaur.
There are only two "bird" starter Pokémon across all of the games and both are top tier Pokémon. Torchic is the other but the Alola region's Rowlet is the best grass starter across the generations. Rowlet earns plenty of points by being an adorable rendition of an owl; however, the best part comes in its final evolution.
Decidueye is a ghost and grass double type which is one of the most creative and interesting combinations across all of the starters. Decidueye is a cross between a massive owl and an archer, making for a mysterious bird that is as cool as it is mischevious. Ghost Pokémon are some of the best around, so having a starter turn into one is a dream come true.