Introduced in Sun and Moon, Poké Ride is a gameplay mechanic lets you ride on so-called Ride Pokémon. As well as being a convenient form of transport, these Ride Pokémon have a wide variety of functions, such as breaking rocks in your path, traversing bodies of water or flying back to previously visited locations.
Indeed, many of these functions used to belong to certain Hidden Machines or items in previous games; thus Poké Ride has effectively replaced them. Even better, Ride Pokémon do not join your party and instead instantly come to your aid when you use your Ride Pager.
You will automatically receive the Ride Pager after defeating Kahuna Hala in Iki Town. Afterwards, you can activate the Ride Pager by pressing the Y button. Additionally, from the Ride Pager menu, you can set up to four D-Pad shortcuts for frequently used Ride Pokémon.
Naturally, not all of the Ride Pokémon are available straightaway. So, like in earlier games, some areas will remain blocked off until you’ve progressed far enough into the story and gotten the contact details for the Ride Pokémon you need.