Ryunosuke is certain that their best chance of getting Bubbles to give up the orb willingly is to do it with Yasuo's help. They're best buddies after all, and after their conversation at the diner it has become pretty clear that Bubbles isn't going to listen to anyone else.

This will probably require revealing at least some of the truth to Yasuo, though how much or how little of that gets conveyed is something Ryunosuke's open to suggestions on. Maybe something along the lines of (this is not verbatim, mind you): my friends and 'I are actually not from Ankata, we're here in the region trying to contain this dangerous wish granting artifact and we suspect Bubbles may have made a deal with it to help you and your team become champion. We need your help convincing him to give up his wish so that we can contain the artifact and keep it from getting into Team Torpedo's hands.' If they have to, he'd want to appeal to Yasuo's sense of sportsmanship and his love for his Cubits to convince him that using the wish to win is just a short cut, and he thinks it's possible for them to be champion material without it.

Since he and his gym partners are already joining the chase atop Kazuma's Gaslord, he'll suggest that the four of them try to catch up with Yasuo and offer him a ride to Doubleleaf if he needs it. They can explain the whole situation on the way.