CONTAINS SPOILERS
"Teambonding" Routine
Once all 4 teammates are obtained, my personal goal is to get them all level 6 friendship with each other so that they all can use "Lend a Hand" mutually. I usually level them up in the Inn until level 4 friendship and then let the "Concern" ability add the remaining. Once level 6 friendship is reached I just let them be at this point, and switch Miis around if they get jealous.