The “Once-in-a-lifetime” Ribbon from Surprise Trading is intriguing. It was likely added to incentivize actually raising a Pokémon that is lucky enough to arrive to you with it, rather than attempting to get it onto one of your own Pokémon (which is nearly impossible outside of hacking of course).
GameFreak probably knows that most people have simply used Surprise Trade fodder to breed their own perfect Pokémon since Gen 6, but now if the Pokémon has the ribbon then one might consider raising it up if only for the rare title. It’s sort of like how they added Marks on wild Pokémon in SS to encourage raising something caught in the wild instead of breeding for everything.
QoL improvements such as the ability to have Egg Moves on anything and the Ability Patch complement this perfectly as well.