The most recent one comes from Reddit user Professor_Wonder. Inspired after rewatching The Incredibles, this fan theory says who the villain will be for the animated sequel. (It definitely won't be Syndrome, thanks to that whole cape/jet turbine fiasco.)
According to Professor_Wonder, the villain isn't going to be some brand new character, but instead be someone from the first film, someone we know and love: Dashiell "Dash" Parr.
For starters, Dash is super powerful, which is also his downfall.
Professor_Wonder points out how the Parr family's oldest son "is always going to be told to [rein] in his superpower." Remember at the end of The Incredibles when Bob and Helen Parr had to keep reminding their son to slow down and get his super speed under control? Kids are impulsive, and teenagers are definitely no better on that front. Growing up, how many times did you do the complete opposite of what your parents wanted you to do?
Moreover, he received positive reinforcement when he acted out in school.
After using his powers to put a tack on the teacher's chair without being noticed (well, almost), his normally melancholy dad perked up and actually smiled and laughed. True, his mom wasn't having it, but Dash paid more attention to his dad's reaction than to his mom's. Professor_Wonder stated, "Dash is able to garner some positive attention by doing something negative."
Basically, mixing Dash's teenage impulses with his desire to be noticed is a recipe for disaster.
Why did Buddy Pine become supervillain Syndrome? The main reason was because he desperately wanted to be Mr. Incredible's sidekick, and the superhero promptly shut him down. Buddy was a teen who impulsively felt like he needed to defeat bad guys like Bomb Voyage, but he didn't give himself a chance to stop and think about the best way to handle the situation. Instead, he dove in and took action, which ultimately backfired. His plan of impressing Mr. Incredible and getting his attention failed. TBH, it's not totally out there to think the same kind of thing could easily happen to Dash as well. Like they say, history tends to repeat itself.