The Pokémon franchise is absolutely massive, with New Pokémon Snap being just the most recent entry. This latest title happens to have the best graphics the series has ever seen. It's not surprising that developer Bandai Namco went all out on the visuals, considering aesthetic is fundamentally the most important part of a game revolving around photography. What really makes New Pokémon Snap's graphics surprising is when it is compared to that of Pokémon Sword and Shield. A graphical upgrade to match the visuals of New Pokémon Snap in the next mainline Pokémon games would be worth the sacrifices that would need to be made.
Pokémon Sword and Shield's sales were impressive, like any mainline Pokémon game's would be, but the games still got a fair bit of criticism. A lot of player complaints toward Sword/Shield were lobbied against the game's graphics. These games brought the mainline series fully into a 3D art style, and many fans were disappointed at the results. Many textures are low quality, and a lot of animations (or lack there of) look odd. Many of the issues with the visuals may be a result of the game's scale. Having large explorable areas and 400 Pokémon before DLC meant a lot of work would have to have gone into making every fully rendered monster have unique animations.
The scale of New Pokémon Snap is much more conducive to increased visual fidelity. New Pokémon Snap's courses are tightly designed, there are fewer Pokémon to animate, and their movements are more choreographed compared to the large variety of moves in a mainline title. This does not necessarily excuse what some would call underwhelming work done by Game Freak on Sword/Shield, but it does show a way the mainline Pokémon games can have improved graphics in the future.
Sacrifices Will Have to be Made for Better Pokémon Graphics
Even Pokémon Sword and Shield left out over half of the universe's total Pokémon. After Sword/Shield's DLC, there are 898 Pokémon in the Pokédex. Many diehard Pokémon fans dislike the continued trend of leaving out a large number of Pokémon, but having so many across all eight generations becomes a huge development challenge. Even if each Pokémon was limited to just four possible moves, that would still leave 3,592 unique animations to be created. If animations are to be improved in the next generation, then the region's Pokédex size is going to have to be seriously pared down.
Cutting down on the number of Pokémon in the game doesn't even address the generally disappointing textures overall in Sword and Shield. New Pokémon Snap is proof that a Pokémon title can look better on the Nintendo Switch, but it could have been any number of issues that kept the textures being higher quality in Sword and Shield. The development cycle may have to be extended, or the entire scale of a mainline Pokémon game might have to be reworked in order to accommodate the graphical quality of New Pokémon Snap.