Many games nowadays have DLC's, which brings me to this question. I'm not talking about free Pokémon events by going to a store or a free Pokémon by purchasing something, i'm talking about a real exclusive game enhancer that can be obtained digitally with money or Nintendo eShop.
MUAHAHAHA!
(Translation: SiIver was right in 2020)
As of December 14, 2023, two mainline and two spin-off Pokèmon games have DLCs. The mainline ones are: S/V (Scarlet and Violet) as well as SW/SH (Sword and Shield), and the spin-off ones are: Pokkén Tournament DX and Pokémon Mystery Dungeon: Gates to Infinity. Here are their names:
Mainline:
S/V:
The Hidden Treasure of Area Zero:
SW/SH:
Pokémon Sword and Shield Expansion Pass:
spin-off:
Pokkén Tournement DX:
Pokémon Mystery Dungeon: Gates to Infinity:
Didn't Pokémon Rumble have DLC by buying crystals or some? commented Jul 5, 2019 by Syl ™
Aside from making fun of weird wording, there have been patches for fixing glitches, which might count as game enhancers. commented Jul 4, 2019 by sumwun
If I remember correctly, Pokemon Quest had microtransactions. commented Jul 5, 2019 by Lepidop
If any of these mean something should be added to this answer tell me in the comments please.
NOVEMBER 2020 UPDATE
SURPRISE!!! Gen 8 has two lengthy DLCs called "The Isle of Armor" and "The Crowned Tundra", so as of today, yes there has been mainstream Pokemon DLC and there's a high chance they may continue with doing this.
I dont believe that any Pokemon game has had DLC before. Particularly main series ones. Take this with a grain of salt.
Edit: Well this comment aged like milk.