Can we get a non-biased list of things removed (or later added again) throughout the generations?

>Generation 2 (GSC)
Following Pikachu (added in Generation 4 again, HGSS only)

>Generation 3 (RSEFRLG)
Day/Night (added in Generation 4 again)
Transfer Pokémon from older generations (added in Generation 4 again)
Phone system (added in Generation 4 again, HGSS only)
Headbutt trees (added in Generation 4 again, HGSS only)
Radio
Apricorn PokéBall crafting (added in Generation 4 again, HGSS only)
Pokégear (?)
Visiting different regions (?) (added in Generation 4 again, HGSS only)
Transfer Pokémon from newer to older generation (?)

>Generation 4 (DPPTHGSS)
Diving
PokéNav (?)

>Generation 5 (BWB2W2)
Following Pokémon
Game Corner
Underground
Ball Seals
Secret Bases (added in Generation 6 again, ORAS only)
Day/Night music (added in Generation 7 again)
Running shoes toggle
Ribbons
Contests
VS. Seeker
Battle Frontier
TMs usuable more than once (?)
Damage from poison out of combat (?)
Berry planting (?)
Honey trees
Pokétch (?)
Pokéwalker (?)
GB Sounds (?)

>Generation 6 (XYORAS)
Difficulty options
Gym leader rematches
Seasons
Gym leader themes
Gym leader final Pokémon music
Hidden Grottoes
Join Avenue
Dark Grass, Shaking Grass, Rippling Water, Dust Clouds
Entralink + missions
Musicals
Pokéstar Studios
Habitat List
Battle Subway
Pokémon World Tournament
C-Gear (?)
Dream World (?)

>Generation 7 (SMUSUM)
In-game National Dex
Dex-Nav
Horde Battles
Triple and Rotation Battles
Super Training
Soaring
O-Powers
PSS
Secret Bases
Bike
Trainer class encounter music
Roller skates
Sky battles
PR videos
HMs
Roaming Pokémon
Gyms (?)

What are we missing?