How Do I Activate the Gen 7/Previous Gen Post-Game Crossover Story?
I've finished playing Pokemon Ultra Sun quite some time ago but I could never figure out how to activate the cross-over story (where Team Rainbow Rocket would invade Alola). I sincerely hope this story is still playable, because that was the sole reason why I bought the game. Sure, the few new Pokemon are cool but I paid $59.99 to fight previous team leaders and past legendaries.
Solution 1:
It should start after getting all the Blacephalon/Stakataka by way of Sophocles going into your house.