I have tried over and over again but I can't even defeat his maquerain and golissopod. My team consists of lvl 40 poliwrath lvl 34 decidueye lvl 34 ariados lvl 35 haunter lvl 35 10% zygarde and level 36 mimikyu
I can think of a few things that might help:
You can replace Poliwrath with a swift swim Wingull. By the time it reaches level 33, it should already have drizzle, air cutter, and scald (TM55 is at Brooklet Hill). Drizzle-boosted scald is good.