Pocketpair has a pretty good case against Nintendo here, I think, because other games have used these things before.
I know it was never actually released, but Scalebound had a mechanic that would have allowed a player to tell their dragon to perform a task, albeit, usually destructively.
Guild Wars 2 Added a mechanic years ago that let players traverse water and land by automatically a switching between mounts.
‘Releasing’ a creature into a 3d environment has been done by every minion-mancer class in an MMO since the dawn of the genre.
You are correct, I missed that it was still under speculation.