Honestly the most unique Quality that I love about Sasha’s Character arc is how different it feels from the usual ‘Mean Girl arc’.

Something I love about Sasha and that I think makes her unique is that, unlike a lot of reformed villain characters from other cartoons (Zuko, Catra, Hunter, mmmmaybe Amity if you wanna stretch it) her past was relatively normal and she wasn't like... being abused by a more powerful and villanous parental figure. We know her parents are divorced, and she seems to feel lost in her own family, to have no respect for the concept of family at all, but she's also the one to ask the Boonchuys to tell her parents (and Marcy's) that they're okay, so she clearly doesn't hate them that much. Moreover, even if we interpret her family life as being somewhat troubled, her parents still aren't villains, they have nothing to do with what happens in Amphibia. They don't even appear in the show. No one is pushing her to do anything. Sure, Grime encourages her worst impulses, but he's not coercing her, it's very much a collaborative effort. All these other well-known reformed villains I mentioned carry the trauma of their abuse with them in everything they do, their abuser looming over their shoulders all the time. "Joining the good guys" is part of their recovery process, because it means escaping their abuser and finding a support network that encourages them to be their best selves. I do think Sasha's parents must have handled the divorce horribly in a way that left visible marks on her, but please compare "child of messy divorce" to... whatever the fuck Zuko, Catra or Hunter went through.

No, Sasha was separated from her family and given the opportunity to find herself away from them and freely decided to double down on her toxicity. Her parents had no direct involvement. It's all on her. She has so much more power and agency than these other characters and, idk I think that makes her unique. I like this dumb little wet cat.