A couple of questions re: pets, and the rover class.

Marnie is a pokemon trainer, and I'd likely be taking her from the end of sword and shield-so she has a full team. Morpeko is the only pokemon she absolutely needs to bring, but I was wondering if she could bring more than one? And, if so, could she switch which is her Rover companion between them while not in the labyrinth (or while within, but I assume that one's definitely a no-go.)