As of release, there is no way to outright switch out a trainer’s Pokemon. It seems as if the sync pair is bonded permanently, at least for the time being. Though that could change with future updates.
Many trainers in the Pokemon game series and anime are known for having multiple Pokemon that they train and battle with. For example, it would make sense for Misty to have a Psyduck in addition to her Starmie.
While it is definitely disappointing to not be able to switch your trainers’ Pokemon out, it is not all doom and gloom. There’s still plenty of variety! You’re able to choose sets of sync pairs before battle, which still gives you some wriggle room with your lineup.
Right now, there are 65 sync pairs, but more will come with future updates to the game. You can collect famous trainers from Pokemon Red and Blue like Brock and Misty as well as more recent characters like Hau and Raichu from Pokemon Sun and Moon.
On top of that, each trainer/Pokemon combination has a different role in addition to the typing from the normal series.
Strike sync pairs have lower HP, but higher Attack/Special Attack. Support pairs have higher HP and the ability to support their teammates. Tech pairs use moves that affect status.
There are even stars and levels that determine a sync pair’s strength. The more stars and the higher the level, the stronger they will be. Some sync pairs can even evolve their Pokemon to make them even stronger.
In summary, while you can’t swap Pokemon in and out for the trainers, you can collect sync pairs if you feel like you “gotta catch ’em all.” Your next step is leveling your pairs up and evolving the Pokemon you can to keep progressing through Pokemon Masters.
