Having different versions honestly never bothered me, I don't mind not having access to specific Pokémon in every playthrough. If I can't get Tyranitar this time around, no problem, I'll just get it when I play another Pokémon game that has it. It makes me excited when i'm playing a game that has Pokémon that were unavailable for me before, and makes me try different mons every time.
What really aggravates me is trade evolution, because it means those Pokémon are never available. Even if trading was something I was interested in doing, it's still stupid that I trade and get the evolution of someone else's Pokémon, and I have to trade back if I just want, you know, to evolve mine. It's lowkey the worst mechanic in the franchise for me, source of so much frustration over the years. Alakazam was one of my favorites as a kid, I took a freaking kadabra to the E4 because that's how much I liked it, and until today I never had it in my team.