So i have a server on Mohist engine with essentialsX and luckperms,also i've added biomes'o plenty.. everything worked kinda fine but i have two issues.. first pokemon spawn rate is kinda low and i don't know if i can change it but more important is that whenever pokemon is about to evolve it evolves into themself (for example mi shinx during evolution have message "shinx is evolving into shinx") and that happened already twice for me and my friends were also saying that they have same problem with their pokemons

Pokemon spawn rate is known and should be resolved for next version. The issue is structure spawns seem to be overloading the spawn, making them slow. You can try editing the pixelmon.hocon file in the servers config folder and change spawn rates there.

As for the evolution issue, it seems to be more common on forge hybrids like Mohist, but still exists no matter your software. It's an issue that's being looked in to but has been hard to track down since there's loads of variables etc. If you can easily reproduce an instance, please make a new bug ticket with exact steps and details.
But for now, your best solution is restart server + clients, update any sidemods/plugins, and refresh any external JSONs if you have them enabled

(also please do not mark tickets as security tickets unless they contain exploits/sensitive information.)
Closing this as a dupe as both issues are already known.