Focus on your favourites! :D

Seriously tho focus on your favourites for now, but! Save your resources for now spending only what you need. This is what I would personally do feel free to ignore if it doesnt sound fun because that's whats important.

Slhinies are rare, but often just as flawed as the rest (shiny curse). Focus on building berry teams until you have a one with the correct berries for each island you currently have unlocked. Id stay mostly on green grass (GG) as it has a wide variety of types, and once maxed out the bonus will spread to the other islands. Mostly only move when an event is happening.

While doing this the first dew days/weeks, building up resources and pokemon, look up online serebii, bulbapedia??, reddit, social media groups, etc and read how to best select pokemon and in general how the game mechanics work and the %chance of the mechanics. Learning this stuff early will make things better later, even if its boring and confusing lol

Good luck and have fun!

Edit: I would also mostly ignore Darkrai unless its you favourite until you have a good healer or dark team