What are your favorite features that exist OR you wish existed in any Pokemon game?
Doesn't matter how small or big, post whatever makes you feel good about a game or improved your experience.
Stuff you specifically don't like is also fine, but try to focus on the positive.

Some of my stuff:
- Gen 3 tilesets and controls. Responsive controls, relatively fast battles, beautiful and versatile tileset.
- Gen 3 secret bases.
- Interactable world via HMs, but not shitting up the moveset of a Ppokemon.
- Visible IVs/EVs and nature benefits.
- Gen 3+ style box management.
- Unlimited bag space.
- Multiple key-item favorites.
- In-game trades.
- Nice variety of Pokemon options early game, so you aren't shoe horned into a team.
- More stats on trainer card.
- Customizable trainercard.
- Generic repeatable quests and dungeons (movement+exploration+battles).
- Battle facilities
- Small pokemon related cultural landmarks like Slowpoke Well or the shrine in Ilex Forest
- Gen 3 diving but the areas need to be more interessting.
- Some secret places like on Route 115.
- A bit more overworld pokemon like in Cerulean City or at Moomoo Ranch.
- Meaningfull transports like the train or boat in gen 2.
- Fixed encounters like Red Gyrados or Sudowoodo.
- IVs should be changeable in some way so you can improve on Pokemon you have played the game with.
- Resettable EVs.
- Museums are cool and they should actually have a purpose.
- Make the player character a bit more like a ranger, that focuses on helping pokemon and establishing new areas, doing "actual research" (archeology, categorization via pokedex)
- Some timed events like in Gen2.
- Safari Zone is a must.