As for mandatory, I reckon there is a 'default canon' party, like Charname, Imoen, Khalid, Jaheira, Minsc and Jaheira in BG1.
In BG3 it's Lae'Zel, Shadowheart, Gale and Astarion. That's the first characters you meet, they have the most content between them, and it's the classic Fighter/Cleric/Roge/Mage party.
I think you might be right. Dark Urge as the MC (seeing how much that character is connected to the main story) and the party consisting of Lae'Zel (Githyanki representative), Shadowheart (Artifact/Shar connection), Gale (Mystra) and Astarion (Baldur's Gate/Vampire noble connection)
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As for Wyll, I remember liking him during the Early Access and wanting to explore the deeper connections he had to the Nine Hells/Mizora (someone correct me if I'm wrong but wasn't there a datamined info that talked about Mizora being a daughter of some bigwig devil) but on release he just turned into a dude that was in my party. The rewrites this game went through aren't doing the story any favors to be honest.
