Marimo

We've seen Sweetie with her parents or at least at her parents house multiple times. In One Bad Apple, after Babs kicks the CMC out of their clubhouse, they have a meeting in Sweetie's room, and we see from the establishing shot that it's not Carousel Boutique but her parent's house, given her dad is outside fishing. In Inspiration Manifestation, Sweetie's with her parents for the Foal and Filly Fair. And Sweetie's standing next to them at the end of A Hearth's Warming Tail.

I think the only parents of a major or main character that could work as a big villain would be either Celestia and Luna's parents, or possibly Spike's.

Except it's not morally grey. It's people unsatisfied that there are still monsters in a world where there are monsters, and their solution is that they need to just revolt against the government and remove the strongest magic users who can defend against monsters. It's like saying your plan to stop crime is to remove the police. What exactly is their alternate solution and why does it actually require to remove the government's top leaders completely, who also do other tasks and not just stop monster attacks, instead of their solution being something that could be implemented with Celestia, Luna, Twilight, and Cadance still in power?

So what, children who are adopted because their biological parents are either dead, didn't want them, or were abusive and forced social services to separate them, those kids can't consider the ones who adopted them as family if they don't share similar enough genes? Blood makes you related, but that's not what makes a family.

Comics did it. #43-45. Twilight declares herself empress and steals other pony’s intelligence to make herself smarter. Rarity wears a cloak and mask and tries to take the throne from Twilight for herself. Applejack becomes a cruel business pony. Rainbow Dash does constant sonic rain booms, causing constant disturbances. Fluttershy controls an army of animals. Pinkie becomes the Joker and plays pranks on everyone.

CMC's got their cutie marks.

Wouldn't the title still give away a pretty big spoiler that Spike has or is getting wings, only now people will know it's not some hypothetical question because it has spoilers tags therefore it must be an actual spoiler? I dunno, he seemed already able to melt a humongous sized ice cloud into water in one burst in Equestria Games.

I dunno, how much does Twilight get paid for being one of the top 4 leaders of the kingdom?

He's Twilight's assistant. I think the point is that she's his superior/employer/boss, whatever you want to call it, since that's the typical relationship an assistant has to the one they're assisting.

I was actually thinking grandfather.

There's no way that wouldn't have been brought up in the writer's summit. And the reason why the box arc was handled that way is because it came down to network and executive demands. The key episodes had to be executed in a way so that they were stand alone and could be watched in any order, not counting the events of the premiere and finale.

When Rarity brought Fluttershy to Rarity for You, she said that the fashion show would be the next day. And by the next time we see her, the fashion show has started. So I guess most of the business for everyone was on that first day, and when the raccoons made it to Ponyville on that second day they had managed to get done or clear up their schedules enough like Twilight in Baby Cakes. And Canterlot is only a bit closer to Manehatten than Ponyville, which isn't taking into account how it would also require climbing up a mountain. Pretty sure raccoons can't get tickets, so they probably had to travel by paw. Plus Rarity would probably only know some basics to talk and understand the raccoons, enough so that they can continue business, but I don't think she understands them enough to understand something a bit more complex and unique like Fluttershy is using multiple personalities to run the shop and they're all mean. So better to chance it on her several other friends understanding. It's a vallery girl accent. That's something that dates back to the 80s.

Similarities in personality has nothing to do with being siblings or related. Heck, all of her siblings are pretty different from each other (Maud is the stoic, Pinkie is the overly happy one, Limestone is the grump, and Marble is the shy wallflower).

For Starlight taking over, it's not a matter of beating the other 5's score since they already had a headstart, but more like how often the focus is on her since her debut. Like if we eliminate the first four seasons, the other 5 and Starlight have both ended up saving all of Equestria twice. But if you also take into account just general focus, Starlight has been a major focus in almost every premier and finale of the show until School Daze (Cutie Map, Cutie Remark, Crystalling, To Where and Back Again, Celestial Advice [albeit as the subject talked about rather than the character herself], and Shadow Play), compared to the others (Cutie Map, Shadow Play, and the movie).

Hasbro clearly wanted to try and set up Twilight. It was right there in the movie how they liked each other and Twilight had an obvious crush. Creative only backed off afterwards, possibly due to all the negative reception it got, and we still had Twilight's Equestria Girls counterpart paired up with Timber Spruce. The timeline with NM's proposed theory doesn't work if you try to fit in Shining and Cadance. Hasbro and DHX decide that they can't pair off the mane six, which leads to them creating Twilight's brother and putting him in a relationship doesn't work if that all comes before they then decide to try and pair off Twilight with someone in Equestria Girls.