>>42657448Fairly easy overall apart from Bruno, of all people. Did you know that his Onix can OHKO a level 52 Alakazam with a crit Earthquake? I certainly didn't.
I finished the pre-National Dex segment of the game with 145 seen and 121 caught, which I think is the most you can get without trading - the only Pokémon I didn't catch were exclusive to FireRed, were trade evolutions, or were only available if you chose them instead of another Pokémon (e.g. Charmander, Jolteon, Omanyte), plus Mewtwo and Mew.
Of the 6 I didn't see:
>Mew isn't available in LeafGreen at all without events/trading>Mewtwo is postgame>Golem is only used by a postgame trainer on Six Island>No trainers use Omastar (or any of the fossils other than Aerodactyl)>No trainers use Scyther or ElectabuzzNow I'm off to do the rest of the Sevii Islands shit and see how much more I can add to my Pokédex without trading.
I know I'm using Alakazam even though I said no trades, but I'd already decided to use Alakazam before I decided to restrict myself by not trading, so I dumped my save and used PKHeX to remove its Pokédex entry. I'm sure this was completely necessary and not at all excessive. 