one year after completing hard mode, the player responds to a flyer they were given by champion empress, she sent out invitations to kanto,jhoto,hoenn,sinnoh,unova,kalos,alola,and galar. she was looking for the strongest trainers each region had to offer so she could form the most powerful worldwide pokemon league. she invited you to test the skills of the home gym leaders as well as the newcomers.

you will be given a choice as to how your new challenge will go you can pick

single battle mode

double battle mode

or

multi battle mode

each gym leader you faced before will be accompanied by returning gym leaders and elite 4 members from previous games, you will be given the choice as to which ones you fight in each room. in the multi battle format, you pick 2 gym leaders to fight alongside each other as well as one to fight alongside you, or you can pick random where your partner and opponent(s) will be random. furthermore, if you fight all members from a certain region you will fight that region's champion at the end of the elite 4. and finally you do not have to only fight one or two leaders in each room, you can fight all of them if you so choose, in fact, if you fight all of them you unlock the secret ending