The Pokémon franchise has undeniably left a lasting impression on gaming culture. This impact is so apparent the Pokémon brand has become one of the most esteemed and well-known worldwide. Part of the reason for the series' overwhelming popularity is the individual designs of each creature in the games. Over the years, Game Freak has made a huge effort in creating Pokémon that not only feel new but also have interesting origins and design history.
While Game Freak hasn't wavered from the goal of producing more and more Pokémon as new titles are released, there is still a noticeable difference between the newer and older designs. Game Freak's design philosophy has seemingly changed throughout each installment, and many of the newer Pokémon are not only very complex but also potentially more intriguing than the series' earlier designs.
It would be ignorant to claim that "every new Pokémon design is better than every old Pokémon design". There are certainly many designs in the first generation that are more complex than meets the eye. Generations One's starter Pokémon are all very unique and original. The biggest stand-out of the original starters, design-wise, seems to be Blastoise; a turtle with water cannons implanted into its shell. This isn't to say that Venasaur and Charizard aren't quality designs, although they both do appear to have a more basic appearance (especially Charizard).
This is a design issue the first generation of Pokémon largely has; some of the designs are too simple. Characters such as Charizard, Arcanine, and Golbat have become immediately recognizable, even to those that don't play games. However, when looking at their design solely, they are undeniably quite basic, closely mirroring their real-life animal counterparts. These designs are far from poor, but in future installments of the franchise, Game Freak pushes the limits of "traditional" Pokémon further and further.
Some of Game Freak's best Pokémon designs come much later in the series. Volcarona, a creature that inhabits the Unova region, is a fire moth with an intricate and beautiful design. It is referred to as "The Sun Pokémon" and its appearance is based upon a solar deity. The antenna on its head also resembles the headdress of an Egyptian goddess named "Hathor," who is the mother of the Egyptian sun god. Another incredible design comes in the form of Sinnoh's Gallade. An evolution from the third generation Kirlia, Gallade's design resembles one of a medieval knight and it's headpiece looks akin to a gladiator. It's battle stance and movements mirror those of a fencer which makes sense given the blades that come out of its elbows. Also, Gallade is meant to be the protector of Gardevoir, seemingly an homage to the code of medieval chivalry.
Looking at these two Pokémon, it seems that Game Freak has a very different idea of what constitutes a complete design. While the designs in the older installments were memorable and iconic, they somewhat lack the scope and ambition of Game Freak's newer creatures. Of course, this is not to say that older Pokémon designs are bad, because that couldn't be further from the truth. However, the Pokémon series has adopted a new design philosophy in it's later installments. Whether this new philosophy is preferred to the classics is ultimately up to the player.