Just on the spot from what I can remember, in the original series:

•  Other animals did exist (the fish in cerulean gym, also fish seen underwater from the s.s. Anne)
• There were aspects of a food chain (like aerodactyl being mentioned as carnivorous, that pidgeotto eats caterpie  I think, also I think the twerps ate hamburgers sometimes if i recall correctly, also fantasizing about eating magikarp after the s.s. anne sinked lol)

Of course these are all just products of very early first series.

Also aren’t there loads of dex entries about predator/prey pokemon? or is this just pokeani canon.

On that note however, do some of these rules, like the death rule only apply to the dub? Cause I’m pretty sure death is mentioned etc. , even recently in the Japanese (fist thing that pops into my head, the Arceus movie, I’m pretty sure ash pleads with it not to die whilst hating humans or something)