>>33635829Gen 2.
-Two new types in Dark and Steel
-Breeding
-Genders
-Held items
-Special stat split, creation of Sp. Def and Sp. Atk stats
-The concept of "special" pokeballs that weren't just straight-up base catch chance upgrades
-Friendship/happiness mechanic
-Pokérus
-Day/Night cycle
This gen did more than any other to shape modern Pokemon gameplay, Gen 4 absolutely also deserves credit for doing a lot as well.
