The Hisui region is Sinnoh long before anyone lived there comfortably. You are surveying it to build the first Pokédex, which means going out and watching things rather than fighting them.

Catching is a skill now

Learn a Pokémon's behaviour, crouch in the grass, aim and throw. You can also toss out an ally to start a battle, but a clean back throw catches things without a fight at all.

Ride across the region

Travel land, sea and sky on the backs of Pokémon, which opens up an area far larger than the series had used before.

It is genuinely dangerous

Wild Pokémon attack you, not just your team, and enough hits will send you back to camp having lost what you were carrying.