I get the idea behind it but now a days they’re just time wasting easy trash NPCs. Replace rivals with an actual antagonist someone or several members of the game’s “gang”

Picture this, the “gang” is trying to steal and find the legendary box Pokémon or they are trying to steal candy from children I don’t care, they send this rookie member to deal with you cause you were at the wrong place or something and you have to battle this bad guy who gets increasingly more competent and better at battles.

He or she isn’t a rival but an active member of the bad guys and they are trying to stop you the player from digging deeper into their plans because through some misunderstanding you’re somehow seen as a spy or something that eventually does want to destroy the “gang” like every other game protagonist does.

Except this “rival” cheats and steals things from you and even uses higher level Pokémon than you given to him by his superiors.

At the end he disappears or changes his way I don’t care.