How to get the achievement: "Supreme Helper Minion" in Terraria.
How to Obtain Supreme Helper Minion Achivement
Complete a grand total of 200 quests for the angler.
Create a journey world and find the angler NPC (Can be found in the ocean biome).
Go to a free item server or world downloaded from the workshop and fill up your inventory with all the quest fishes.
Go back to the angler and click "quest". It should take away one of your quest fishes and give you some reward. Since you can only do one quest a day, I recommend changing the speed of time to 24, or repeatedly changing the time from midnight to dawn. Do that until all the quest fish are gone, and then return and get more.