Here's a little tier list for each character to show how I think of each one: S-Tier: Kris - They literally neg every phase of Frisk/Chara and make Demonic mode a joke. A-Tier: Asriel - Can kill normal Frisk/Chara with no difficulty but can struggle a bit with phase 2. B-Tier: Corridor Chaos Papyrus - Like normal Papyrus, he's amazing on Easy and Medium, but sucks on Hard and Demonic since blue soul randomly gets negated by phase 2 for some dumb reason. C-Tier: Dusttale Sans - He's alright. He struggles on Medium 3 and he's about as powerful as Asgore.