If they both end up getting one, the t hat is how I would expect it to go. Though I think Goh catching one would add another great pokemon to his team, but I am less excited for Ash possibly getting one because I don't think it would really add much to his team.
I think that he is more likely to catch a Gigalith than for us to get a trade back episode.
Given that steel is the last type he caught, he really has been catching them rapidly.
I don't thing anyone will catch Alcremie.
Goh needs to catch more Dark, Dragon, Ice, and Fairy types.