>>57355957Rival who starts off stronger than you. And not in the, oh I am stronger than you but I will go easy way, but in the you lose your first confrontation with him way. After he beats you, he steals something important from you such as a key item or maybe even your starter Pokemon. Then much of the game revolves around a man hunt for him so you can get your shit back. If I am going with he steals your starter Pokemon idea, the next time you battle him, your starter is in his party fully evolved being used against you. Obviously this character wouldn't serve as the primary rival.
Another Idea is a copycat rival. Every time you beat this rival, he gets jealous of your "overpowered" team. He then catches and uses a mon that was a mon you used against him during your previous battle, lets say whichever one had the highest stats. So if you beat him with a Bulbasaur in your first fight, the next fight he would include a Bulbasaur(or evolution) in his next fight. If you beat him with a Medicham in that fight, the next fight he would include both a Bulbasuar and a Medicham. He will eventually have a team comprised of mons you have used in your battles with him. He will have dialogue differences based on if your team is the same as his or not. I guess he would have to stop doing this once the player is able to catch legendaries, maybe by the point he will realize that he can't have a powerful team just by copying you.