The method I will introduce you to is so gamebreakingly overpowered that it could be considered an exploit and should under no circumstances be used on a first playthrough of the game as it will ruin ALL enjoyment you could have with this game. Do this on your second playthrough when you are going for this achievement as well as the Legendary difficulty mode or you dont give any s... and just want to breeze through the game in the shortest amount of time possible will boring yourself to death.
The tools you will need to pull this off come late in the campaign and include:
Jade Staff, 18 Arhats Amulet, Monk Shoes and a fully specced Seal of Attraction skill tree.
Once you have all that load chapter one Eight Diagrams level and proceed to hold down left trigger while spamming b as fast as you can whenever enemies appear on the screen while watching the game turn into a one button spam simulator. Dont tell me I didnt warn you.