>>35219748National Dex.
No, but for real:
Seasons (gen 5)
Roaming Weather (gen 5)
Grass/Water/Dust Spots (gen 5)
Following Pokemon (gen 4)
Pokewalker (gen 4)
VS. Seeker (gen 3)
Phone/Gym Leader Rematches (gen 2/4)
Underground (gen 4)
Chain Fishing (gen 6)
Apricorn Balls (gen 2)
Berry Pots (no one ever thinks about these, but they were fun) (gen 4)
EV Training Games (gen 6)
Literally anything approaching a contest, including Pokestar and Pokeathelon, but not Pokemon Musical
Battle Tower/Park/Frontier, even Maison or Subway (gen 2/3/4/5/6)
Pokeball Seals (gen 4)
Triple Battles (gen 5)
Side quests in post game
FUCKING ARCADES
They dropped so much good shit from gens 4 and 5, it was absolutely insane. And Gen 7 basically brought almost nothing to the table. Nothing good anyway. Pokeriding is fucking awful, but I'll accept USUM Mantine riding as not being that bad. And the Battle Tree was a good idea, but it was done better with the World Tournament in 5th gen, honestly.
I could literally go on forever, but I need to stop being angry at some point.