Sorry, I didn't notice how the translator wrote "monkey", but what I meant was that I definitely need to fight him, level 15.
With the level 15 version
With an assimilating avatar
The best tip I can give you without spoiling too much is to look at your Skills, there is some that are very helpful in that battle. It depends in which part are you having problems. If you want me to be more specific and tell more specific tips, then please ask in the Spoiler topic here: https://dmquetzalli.itch.io/delve-into-pawssion/devlog/382260/guides-and-secrets...