No, it's not chibi -- that's more extreme, turning characters into big-headed caricatures with babylike proportions, also called "super-deformed." The original Teen Titans animated series would often have its characters transform into chibi caricatures of themselves during the more comical moments, and the standard character designs of the Teen Titans Go! version are evolved from that. As I said, She-Ra has more of a Sailor Moon/magical-girl aesthetic. She-Ra's transformation sequence is very Sailor Moon.
Also, I don't know how you're using "rotoscoped." That word means to trace live-action footage to create animated characters that move realistically.
The 2011 Thundercats was very different stylistically. That was very anime-influenced, but in a more realistic and detailed style. There was nothing remotely chibi about it. Maybe you're thinking of the upcoming 2019 Thundercats Roar! reboot for Cartoon Network, which is going for a much more cartoony, comical look that has some similarities with chibi.
Also, I don't know how you're using "rotoscoped." That word means to trace live-action footage to create animated characters that move realistically.
The 2011 Thundercats was very different stylistically. That was very anime-influenced, but in a more realistic and detailed style. There was nothing remotely chibi about it. Maybe you're thinking of the upcoming 2019 Thundercats Roar! reboot for Cartoon Network, which is going for a much more cartoony, comical look that has some similarities with chibi.