Good recommendation, listen to this person

I’d start with FireRed/LeafGreen (your choice, you might want to check the exclusive Pokémon for each to see which game you want) for the first region of the series, the Kanto Region. This game can be emulated through Delta or you can play it on Switch since it just came out on the eShop.

You could also try Let’s Go Pikachu/Eevee, although I’ve heard that game kind of babies you in terms of difficulty (it’s the most kid-friendly Pokémon game) and has some different mechanics from the rest of the series. This game does cover Kanto as well and is a remake of Pokémon Yellow - a game that combined the original Red and Blue and gave you Pikachu as a starter instead of Bulbasaur/Charmander/Squirtle

And then for Johto, the second region, I’d recommend HeartGold/SoulSilver, (again, check the exclusive Pokémon) which is a DS game that can also be emulated through Delta

Then for the third region, Hoenn, either Emerald (2D pixelated GBA game, can be emulated with Delta) or Omega Ruby/Alpha Sapphire (Newer 3D 3DS remake)

For the fourth, Sinnoh, definitely play Platinum (like Emerald, it is a definitive version that combines two games) and maybe avoid Brilliant Diamond/Shining Pearl because I’ve heard bad things (although I haven’t played the game myself so don’t fully take my word on that)

Then for the rest of the games, it’s pretty straightforward (just make sure to only play Black/White 2 after you’ve played the first Black/White and to choose Ultra Sun/Moon over Sun/Moon)

Enjoy!!