Another fellow here who didn’t get into pokemon as a kid. I had a gameboy, but never got a pokemon game for some reason :/
For original entries in GBA/DS realm I’d play the third version (emerald & platinum). With remakes or gens without the third version, I wouldn’t stress too much about what to buy.
If you’re buying legit carts, then just get the one that you can find for a good price. Alternatively if a game has version exclusive pokemon that you really like, get that one.