>>51004890The biggest reason is that Pokemon is literally the biggest brand in existence. No matter what another company tries to do, Nintendo/TPC can always out-muscle them in pure advertising.
I think the closest a series came to "killing" pokemon was Yo-Kai Watch in its prime, (at least in Japan) since it went in hard on the storytelling, game polish and the anime in ways that Pokemon had fallen short in.
Of course, Pokemon responded not by making their games better but by going in even harder on Branding, bumping up the anime budget and merchandise to muscle out the competition.