What's the general consensus on Cackletta?
Due to her sidekick Fawful being much more prominent in the series, and having a much more unique dialogue gimmick of speaking like a bad translation, Fawful is talked about a lot more often than Cackletta.
While I do think Fawful is better, I think Cackletta is a pretty good villain on her own. She's very threatening, prominent throughout the story, and can be just as funny as funny as Fawful. A witch isn't really a common main villain in the Mario series and her "evil fairytale"-like actions like stealing someone's voice and body is really creative. The transformation into Bowletta and Cackletta SOUL also really ups the stakes and is a fun plot twist.
I also really like how Cackletta dies halfway throughout the game and is a lot more prone to making mistakes than other villains, she gets tricked by the heroes like three times before her defeat. She's kind of at a disadvantage for most of the game. It might make her seem incompetent but her violent reactions still make her a theeat.
Her mid-game and final fight are also pretty scary for a Mario game and I like how incredibly unfair her final boss fight is by putting you at 1 HP.
I think she's one of the stronger villains in the Mario series, like high B-tier or low A-tier. She's not the exceptional at one thing but she does everything very well. Funny, threatening, large amount of screentime, pretty unique, I think she's good.