Rematch the Gym Leaders and the Elite 4

After obtaining the National Pokedex, Roark will visit you outside of the Pokemon Research Lab, inviting you to challenge each Gym Leader once more to defend your title as the Champion of the Sinnoh Region.

This time around, however, the Gym Leaders are much tougher than they were when you first battle them. All of them have six Pokemon, each no lower than level 60. Make sure you got your team ready for these rematches; they’re all essentially Elite Four-level trainers.

You can rematch the Elite Four and Cynthia for a second-round as well—their Pokemon will be much more challenging too. You can rematch the entire Pokemon League for one final time after defeating all of them during the first rematch.