After the upcoming episode "Guzma the Undefeated!" end, the narrator said "major world exclusive announcement! Get an early look for the new Pokemon from the new game titles Pokemon Sword and Pokemon Shield!

It's a mini-arc for anime after the league

The trailer show Oleana arriving at the Alola then switch to the next scene where she said she came to Alola to see if someone in this league is "worth" than showing a quick shot of Galar region before switch to the next scene where she battling with Gladion's Lycanroc using her Corviknight then switch to the next scene showing she about to leave but Ash stop her and say he want to battle her, she said Ash is not worth for her and ask for a reason why she should battle him then Ash said to the camera "Because i want to become a Pokemon Master!" trailer end.