A little thing I like is that all five Pokemon who have ever been a starter in a Kanto game, between the traditional Grass/Fire/Water trio Bulbasaur, Charmander, and Squirtle, and both non-traditional starters (Pikachu and Eevee) who are shared mascots from Yellow and the Let's Go games, together embody the five element concept common in many fictional settings and stemming from both Greek philosophy and Japan's Godai philosophy. Those five being Fire, Water, Earth, Air, and Aether/Void. Bulbasaur represents
Earth, Charmander represents
fire, Squirtle represents
Water, Pikachu represents
Air, and Eevee represents
Aether or Void.
Altogether, they embody the elements and their gameplay design reflects the individuality of the elements that is often common in fiction.
The Bulbasaur line represents
Earth, because as Grass-types, they have dominion over plant life and energy. The Bulbasaur line is perhaps the best example of this, and in many media we've seen them capable of manipulating nature and plants (and by extension, the earth), and as such the Grass-type represents Earth. Earth magic tends to be defensive or support oriented, less so at offense, but is not always the strongest offensively, even if it can in some ways be the strongest element overall. This is very evident with how Bulbasaur is designed gameplay wise. Earth potentially being the strongest of the elements is reflected in how great Bulbasaur is in Kanto and how it is the strongest in the early game: it has an advantage against most early opponents. But its big standout among all starters is that in line with the earth element being defensively oriented, the Bulbasaur line from the get go is geared towards support. One of the first moves it learns naturally is Leech Seed, which does passive damage in exchange for healing Bulbasaur's HP little by little. It also starts learning powder moves like Poison Powder, Stun Spore, and Sleep Powder, all to inflict status conditions that either do passive damage or incapacitate the opponent. In later games it starts to learn healing moves like Mega Drain or Giga Drain, as well as Synthesis. But it is also capable of delivering powerful blows with its STAB: while Grass isn't the best offensive type, and why Venusaur is a tad oriented towards defense, it can deliver strong blows. Back in Gen 1, it had the highest Special of the starters, and it had a stream of strong STAB moves in Razor Leaf (high critical hit ratio) and then its ultimate move, Solar Beam, a 120 BP attack. Its Mega Evolution amplifies its more defensive properties, giving it a substantial Defense boost while changing its ability to Thick Fat, which halves damage from Fire and Ice moves (a defensive ability).
The Charmander line represents
Fire, although admittedly that is obvious given they are the Fire-type. The Charmander line, in contrast to the Bulbasaur line, is very strongly offensively oriented: they're frailer, but faster, and have more offensive punch and a wider offensive movepool, making them more of a glass cannon, but one that dishes out a lot of destruction from the get go. Charizard also distinctly had the highest Speed of the trio back in Gen 1. Charmander's level-up movepool is very much about powerful attacks. Fire is a more offensive type with its ability to hit many things super effectively. They tend to learn a variety of attacks like Earthquake and Slash back in Gen 1, and in later generations moves like Air Slash, Focus Blast, Dragon Pulse, and vice versa. It's also the hardest to use in Gen 1, with its disadvantages in the early game and a long mediocre period between Ember and Flamethrower, representing Fire being hard to handle. It has two Megas, both of which hammer in the offensive side of things: the traditional Y Mega has Drought, increasing the power of Fire-type moves with sunlight, and gains a substantial Special Attack increase to add to it, while the X Mega has Tough Claws, and gains more of an Attack boost, making it a formidable physical attacker.
The Squirtle line represents
Water, also obvious like with Charmander. The Squirtle line represents Water's fluidity, or as I shall say, flexibility. This line is very much a blend of offense and defense that it harnesses both. As a Water-type, it has great all around offensive power with moves like Water Gun, then Surf and Hydro Pump later on, and Water has strong coverage, and back in Gen 1 it had good offensive stats to go with it. It can also learn Ice-type moves, and in later games, a lot of pulse moves. They can learn defense boosting moves like Withdraw and Iron Defense, as well as Protect and a hazard removal move in Rapid Spin, giving them durability to play slightly defensively (they also had the highest Defense of the starter trio back in Gen 1). In later generations, they can also learn Shell Smash to become a more powerful attacker. Blastoise's Mega Evolution offers a substantial Attack boost and boosts its own bulk to become a tank, and its ability Mega Launcher allows it to deliver stronger blows.
Pikachu has occasionally been a starter, and oftentimes the *only* starter in the games it's actually a starter in (ie Yellow and Let's Go Pikachu), mirroring the anime making a creative liberty of giving Ash a Pikachu as his starter. Partner Pikachu cannot evolve so it stays as it is. But it represents
Air. A slightly tenuous one, but when lightning isn't an individual element it's often classified with air, since lightning forms from the reaction of air particles, which is why Electric-type fits. Air elemental types in most media tend to lack raw power and are very frail, but are very fast: this is basically Pikachu's statline in a nutshell and the Partner Pikachu in Let's Go Pikachu is an upgraded version of this. Pikachu is frail as glass and doesn't have raw power per se, but it's fast, and it can strike first with its attacks, even knowing moves like Quick Attack, Agility, and Double Team naturally. It has a Z-Move that is a nuke button, which is more or less in line with it being offensively oriented as a fragile speedster.
Finally, Eevee represents the most unconventional "fifth element" that often doesn't get acknowledged much because of its unusual nature. But it represents
Aether/Void. It is representative of something that is both nothing and everything at the same time. Empty space, yet unlimited. This is represented in the concept of infinite possibilities. Eevee's whole gimmick is that it's a blank slate, being a Normal-type, the non-elemental type, but with unstable DNA is able to evolve into many different Pokemon, all with different, more elemental types, meaning it has many possibilities as to what it can become. While Eevee has only ever been the rival's starter in Yellow, and a playable starter in Let's Go Eevee, this is represented well in both variants. The rival's Eevee in Yellow can become one of the three Eeveelutions that existed at the time depending on the circumstances of the first two battles. The Partner Eevee does not evolve but has an all-rounder stat build and can learn a variety of unique moves that are all the types of its Eeveelutions, representing each and every one of them. Not evolving also represents the alternate possibility of not needing to change at all. It also happened to obtain a signature Z-Move in the prior Gen 7 games that is a sharp omniboost to all five stats, and playing on its many Eeveelutions flavor wise.
As a whole these five embody a five-element ensemble quite nicely and have the gameplay design that embodies their individual respective elements well and gives each of them a sense of individuality, which I think is pretty cool.
