Pixelmon Mod

My Pokémon server gets stuck on the battle interface during battle, unable to defeat wild Pokémon.

We'd need more information to help you.
Which Pixelmon version are you playing on? Are you able to type the command "/battlelog" while stuck? If so please upload that log to something like PasteBin and link it here. Also please link your general "latest.log" file as well, regardless of whether you have a battle log or not.
(How to find your logs: https://pixelmonmod.com/wiki/Finding_your_logs)