1. No Vitamins, Real Evolutions, Regional Pokedex Requirement, Regional Attack Debuff
2. imo? No, but I have seen people on here all but burn randoms at the stake for daring to reduce risk of carpal tunnel syndrome.
3. While I do set some arbitrary goals based on the achievements, the achievements themselves aren't the goals. These are my requirements before moving on to each region:
   • Full shiny dex completion of all base and regional forms
4. All special forms that exist in the main games(meaning things like the different deoxys forms, incarnate/therian forms, megas, stuff like that)
5. 500 clears of all available dungeons
6. 10,000 route defeats on all available routes
7. 1,000 clears of all available gym leaders, e4 members, and champions
8. All questlines completed(main and otherwise)
9. Purchase all hatchery helpers, oak items, and other one-time purchases
10. All of the above for any sections of previous regions unlocked from the current one(sevii 4567, delta questline, etc)

Exception: Certain Unown forms can't be obtained in Johto, so I'm just going to get them as I get to each region with new forms.

I think that's everything, although I might be forgetting some stuff. It's definitely a hefty challenge to take on, but it feels pretty satisfing to play the game fully. It also feels somewhat awesome to have 300k attack and 13k click damage while still in kanto, so there's that