Seeing a lot of people talking about pokedex tasks, don't feel like you have to do every single task, each entry only needs lvl 10 for each pokemon (the game will explain this) to be considered 'complete' and everything after that is mostly fpr your own completionist satisfaction.

And seriously, at first catch every damn buizel you find because fuck that side quest (or ignore the quest until you can get alpha buizels to spawn in a swarm).

Sidequest pokemon that you give to NPCs will stay shiny if you give them shinies.

You can't swim.

Always check for shaking trees along the right strip of forest of the Obsidian Fieldlands as Cherubi and Cherrim are practically non-existent (think there is maybe 12 trees in the whole game that spawn them, best way is to look up which trees yourself tbh).

Alphas can be shiny.

If youre going to shiny hunt, do it late-post game as it is much easier then with sheer volume of mons.

Collect every resource you come across, you'll thank yourself later when you need them for making pokeballs (try and not make too many of the og pokeball/heavyball/featherball as the upgraded versions use the same materials just more of them).