Later in the game after you can reach Iccirus City, you go in the old gym.There are no trainers there, so you don't really have to revive your Pokemon. After you pass the giant ice puzzle,Brycen will be at his spot like the last game.Talk to him and he will talk for a while.At the end he will leave.
After that you can act in Brycen Man 2.Your rental Pokemon riolu,will have evolved into lucario.
