>>49911140I think, first of all, all pokémon have seaming endless lifes because they're energy entities.
(How they can become bigger just in less than a day or make attacks with fire or electricity.)
But they can be hurt and even killed.
About natural death, just i remember the anime and that's another story. But in games all the deaths are more for the situation or caused by someone else (ex: Cubone's mother killed by Team Rocket) maybe galarian corsola but that also came back as a ghost of itself. Which speaking of ghosts also explains their existence.
Psychic and Fairy are known for their long lifes.
>Florges who can live like 300 years. 
