An idea would be on the way to Alola while on the boat a Ultra wormhole opens and the MC has the choice to go in (while he does not have any legendries) he would arrive at a Ultra Nexus (place to choose where to go) with multiple portals to choose from and each would have a Ultra beast in a different alternate world. The worlds could be strange like no gravity places , you know places that don't make much sense but in there it is normal. When he comes to the portal that would lead home the option to leave would come up and he would know he would not be able to come back. When he does get back only a few seconds passed so none of the other legends are worried yet and all goes fine.
For the tasting it could be a bottle appears with a picture of the Ultra Beast with milky breasts and say "This is something to remind you of me and I already have plenty of children to remind me of you".