Here’s potential for you : One-shotted the final boss with Red using her Level 2 Burst. She basically has made the game trivial once I got her. I don’t even bother with Stealth, just focus on Crit and Crit damage abilities. The revolvers she gets from Caldeus around 20 make the rest of the game a total breeze.
Bretto is amazing once he gets the Level 19 weapon with Invigorate on it (10 overcharge per turn). Couple that with the Overcharge healing Perks and go to town. I was still using that weapon at the end since it worked better for synergy than the Ultimate weapon.
Gully is easily the best tank in later levels, but I’m sure it doesn’t have to be her. I just kept slapping on Stam to her with Stam perks and she’s unkillable.