Can I just say I agree with most of these, especially removing trading and lowering levels? And I'd like to add a few more:
Feebas to Milotic: High friendship, level 20 just like Magikarp to Gyarados, or just level up with the Prism Scale. Adding a new trade evolution so late was... not Game Freak's brighest idea.
Rockruff to Dusk Lycanroc: Have it evolve at sundown hours regardless of Ability.
Combee and Salandit: Have them evolve regardless of gender, but give the males new evolutions. Something like a crawling grave-robber for Salandit, and a white-knight drone for Combee.
Espurr to Meowstic: Remove the gendered requirement; have the female form be a daytime evolution, and the male form be a nighttime evolution.
Exeggcute to A-Exeggutor, Pikachu to A-Raichu, Cubone to A-Marowak: Alola Stone. Alternatively, Sun Stone for Exeggcute, (level up with) Big Malasada for Pikachu, and Reaper Cloth or Dusk Stone for Cubone.
Koffing to G-Weezing: Galar Stone or an exclusive item - Air Purifier, perhaps?
Scyther to Kleavor, Stantler to Wyrdeer, Ursaring to Ursaluna, Goomy to H-Sliggoo, Quilava to H-Typhlosion, Dewott to H-Samurott, Dartrix to H-Decidueye, Rufflet to H-Braviary, Petilil to H-Lilligant, Bergmite to H-Avalugg: Hisui Stone or Hisui/Historical Scroll.
Pokémon who got regional forms with evolutions when the originals have none like Qwilfish, Corsola, Linoone, Farfetch'd, Mr. Mime and Basculin: Have them evolve into new forms too, to level the playing field.