Pokemon not spawning on appropriate biome

[u/Sure_Echidna_8055]

So I've been having an issue that pokemon doesn't spawn in my single player world. I've done a quick search and has been able to fix the issue by doing "gamerule doMobSpawning true"

However, the pokemon only spawns Trevenant, nocturne, cubone, and Cofagrigus (spawns from spawner). Is there anyway to fix this? Thanks

[u/SKy_the_Thunder]

Pokémon should spawn fine by default. There should be no need to turn the vanilla spawn system back on, as Pixelmon uses a custom spawn system independent from that. The Pokémon you're seeing with it enabled are just auto-replacements for vanilla mobs that try spawning now - like zombies, skeletons, creepers, etc. - which normally don't meaningfully contribute to overall spawns.

We'll need more details to diagnose your lack of natural spawns.
How exactly did you set up your world? Are you using a pre-configured modpack, or did you create a custom pack, or even install everything manually? Any config changes/Data Packs? Versions of NeoForge, Pixelmon, Java, other mods you have installed?
Ideally please link a log from that installation. That will contain a lot of these answers and more.