South Park The Fractured But Whole - Farts over Freckles Trophy / Achievement Guide - Pick a fight with Morgan Freeman (Boss Fight) and defeat him.

To fight Morgan Freeman you must be playing as a white character. He doesn't fight black characters.
You can change your skin color with PC Principial in Crunchy's Micro Brew in the North-West of South Park.

This can still be done after the story!

Now go to Freeman's Tacos on the Main Street. Get behind the counter by pressing X (PS4) / A (XB1) on the left side of the shop. Then attack Morgan Freeman from behind to trigger the boss fight.

He is a very tough boss with 9999 health and can charm your allies to fight for him. He also summons a few minions during the fight.

Since this boss fight is going to last a long time you should equip the Plantmancer's class Ultimate Power called "Nature's Gift". It will let you revive all your comrades on the field and also heal them. Always use this move as soon as the Ultimate Meter is full.

For characters I picked Callgirl (she can attack at any range), Mosquito (he can self-heal with each hit), and Fastpass (he can turn invisible so can stay alive for longer).

It's highly recommended that you attempt this only after the story. Before then it's way too hard. I had a total artifact strength of 791 for this fight.