As a kid I completed the Pokedex in Red version by trading the like 8 pokemon you couldn't catch with my friend, and he reset but didnt save so we grabbed the starters I was missing so we did it together
We wanted to do it in GSC too but we both wanted Scizor for our teams and petty so much second they added in shit like "you need trad evos, one-use item evos, AND version exlusives plus baby forms you need to breed, and some pokemon evolve via happiness, etc" it was just too much hassle we never bothered doing it all
So yeah gen1 it was doable but every game past that adds too much boring annonying shit, and by the time you get to like "win 100 online battles for Spiritomb" or whatever like no one is going to bother
