Bulk store multiple pokemon from Sw/Sh to Pokemon Home at once

CP
The Pokémon's CP is kind of maintained when transferred into Let's Go. When you interact with the Pokémon, it will initially display the CP from Pokémon Go. After the Pokémon is caught, the CP will change. The new CP is derived from all the stats combined. (Source)

Level
The Pokémon's level is maintained when transferred into Let's Go. If the Pokémon was caught via a raid, it will be lv20 (or lv25 if weather boosted) when transferred into Let's Go. (Source)

Nature
The nature is randomly generated when you capture, not transfer, the Pokémon. You can catch/reset until you obtain the desired nature. (Source).

Inspired by Ellesedil comment, you can use the Fortune Teller in Celadon City to manipluate the natures of Pokemon within the Go Park. (Source)

IVs
IVs are carried over and translated into Let’s Go equivalents. While Let's Go does not display the actual IVs, there is a formula used to calculated the IVs after transferring.

• Hit Points = Stamina IV * 2 + 1

• Attack & Special Attack = Attack IV * 2 + 1

• Defense & Special Defense = Defense IV * 2 + 1

• Speed = Randomized

(Source)

Moves
The Pokémon's move set is not maintained when transferring into Let's Go. It gains four moves, and is not guaranteed to posses the move set from Pokémon Go.

Shiny
Shiny forms are maintained when transferring into Let's Go.

Alolan
Alolan forms are maintained when transferring into Let's Go.

Galarian
Galarian forms are not supported in Let's Go. The Let's Go series supports up to Generation 7 for Alolan forms while Galarian forms are Generation 8. (Source)

Lucky
Lucky status is not maintained when transferring into Let's Go. In regards to Let's Go, the luckiness only ensures the Pokémon will have high IVs. (Source)

Costumed
Costumed Pokémon cannot be transferred into Let's Go. This includes:

• Sunglass Squirtle
• Hatted Pikachu
• Hatted Eevee
• Armored Mewtwo

Shadow/Purified
Shadow or Purified Pokémon cannot be transferred into Let's Go. (Source)

It's similar to raising affection in the 3DS games - play with them until their play meter is maxed out, then feed them, then go back to playing. It's a little more efficient now as you can raise two at the same time. This is the method that works best for me:

1. Set up a Pokémon Camp
2. Face the two Pokémon you want to raise and Call them over to you
3. Get out the feather/bell like cat toy and wave it around (I just mash the A button) in between the two. The two Pokémon will attack it over and over, each time letting off some orange notes
4. After a while, the Pokémon will stop attacking, stand still in place, and release a speech bubble with orange notes in three times in a row - they are now ready to move to the next step
5. Cook a curry - I don't think the quality matters too much, but it doesn't hurt to aim for a nice one. Wobbuffet or higher should be fine, though
6. Go back to step 2 and repeat
7. At various points throughout this procedure you will see pink hearts instead of orange notes - this indicates they've gone up an affection level. Once they reach the maximum level, instead of orange notes at step 3, you will get nothing at all - this indicates the affection is maxed out

It's useful to max out the affection as soon as you get anything you're planning on keeping in your party. Especially a Farfetch'd/Sirfetch'd - with maxed affection and holding a Leek, every single attack it makes will be a critical hit!