how does C6 skirk hold up against stygian fearless/dire?

considering in C6ing her because i love her but i also know she's insanely strong at C0R1 (what i have atm). is there ANY boss, even ones super shilled for other things that she can't do at C6 with C0 supports? or is C2R1 good enough to go through basically everything in fearless? ty in advance (for ref, i have c2 furina and c0r1 effie, and c6 mona no shenhe)