One guy on Youtube's Oshawott hasn't evolved yet! Maybe he doesn't want to, but he never received a message asking if Oshawott was going to evolve! Does it work differently than regular Pokèmon games?
Evolution is different compared to all the other Mystery Dungeon games in this game you can actually evolve any Pokemon on your team in any dungeon if they met the requirements. But you and your partner have to wait until after the events at the Worldcore dungeon and 1 more dungeon from anywhere. Once that is done you can now evolve yourself and your partner