Nintendo and their lawyers can go suck an elephant dick.

From part 8 of the newest doc

the boarding character is selected among a plurality of characters the player character owns in association with providing a second operation input when the player character is in the air, cause the player character to board an air boarding character and bringing the character into a state where the player character can move in the air

and while the player is aboard the air boarding character, move the player character, aboard the air boarding character, in the air based on a third operation input

Plurality of mounts and “second operation when in the air” ain’t new, World of Warcraft had that in 2007 with Burning Crusade. I have no clue what “third operation input” means there.

A lot of the other alterations seem to focus on “air boarding character”, probably because they realized that you can only change your mount in Palworld manually while on ground or water, which kept glider pals safe, as they were the only ones you could summon while in the air.