Whew, that's a lot. Now to tell you what's wrong with everything you said.



First off, your presumption that he taught Sunset Shimmer how to play the guitar is not only just that, it doesn't even matter. It's a detail that has no impact or meaning.



Flash doesn't have a sense of justice, he merely has a moral sense of right and wrong. Judge Dredd has a sense of justice -- that is doing justice for justice's sake. Sometimes morals can be out of the picture entirely. Even so, the only reason you can even assume that Flash has a moral sense is because the same can be said of about 89% of the rest of the characters who ever appeared in the show. Saying he has a "sense of moral" is not only akin to saying he breathes oxygen, it's really not even satisfying. Really, you'd be better off to bring up that he's got a sense of fashion. Flash not holding grudges is also another pointer of "oh that's so unique I've only seen it fifty times already." You keep picking at these tiny traits thinking they make a world of difference, but in reality you don't describe anything that sets Flash apart.



A character flaw is something that has an impact on a character, something that presents a challenge, a meaningful obstacle -- not being able to cook is not a challenge unless he's like Bender and wants to be a big time chef. The same can be said for being a klutz and having an ego (which, once again, is not a unique trait in the least), an bringing up the band name is a desparate move on your part because we're not even sure he named the band -- it's entirely possible his bandmates named it. At worst, he has all the ego of Josie from Josie and the Pussycats.



Of course he was smart/talented/athletic enough to be in the Friendship games. If he were a decent fighter he'd fulfill all the criteria for being a Gary Stu or a Marty Stu or whatever you call it. He's crafted to be a perfect "cute guy" character -- and yes, his clumsiness plays into that because it is there to make him cuter. Flash's friendships also hold no importance, especially considering the characters he's friends with are no better than he is.



Flash may end up becoming a police officer in the human world, but that's just an occupation. It doesn't fix what's wrong with Flash. I'll discuss that more later. Odds are Flash is the same on duty and off -- he doesn't get all 'Soldier' and serious (that would only make him more annoying honestly) he likely acts just like he already acts. He's so vague a character he doesn't even require a different mode of personality.



As for "Popfly" I don't care about him or if he is Flash's younger brother. That has no effect on Flash, at best saying he might have a younger brother, but Flash by his lonesome is still boring as all get out.



As for your message to Flash-Haters:



- Derpy, Lyra, DJ Pon3, Berry Punch, etc... these were background characters who stood out and did something. They caught the attention of the fanbase for doing something entirely unique and unusual and the fans fell in love. They didn't need to be fixed, they were perfect because fans saw them do something and loved that thing and stuck with it. These characters offered some insight into themselves and fans ran with it to flesh them out.



It's also important to remember they were background characters.



Flash is a secondary character who is supposed to be just as important as the Mane 6, but as a character he doesn't stand out, he doesn't offer anything unique, and even worse is he doesn't hold the promise for it. Fans insist he can be given the same treatment as the background ponies, but the difference is that the background ponies were perfect from their inception - Flash's problem is that he's so painfully generic that even his fans have to convince themselves he's just at a rough spot.



As for Scootaloo being an orphan, I don't think that's canon. Even if it was, that's still not the same thing.



You say 'Cliche' does not define one's entire personality, but it does with Flash. Flash is not only a cliche, but he is an outright stereotype. Flash is literally defined by every trope of what you'd expect from a pretty-boy teenager from a teen-drama would do. It's literally what he was made to be. Even his royal guard self was made royal guard to make him a knight in shining armor. The entire point was to make him a 'Prince Charming' of sorts.



The Mane 6 aren't cliche at all, and I've no idea where you got that idea. Simply having a common trait is not a cliche, otherwise literally every character ever written would be one. A cliche is when a character outright unoriginal. The Mane 6 do pretty well to remain unique and memorable. If it hadn't been for FlashLight, no one would remember Flash.



Actually, people would have cared if Flash had been a female. Just look at how much they hated Sunset Shimmer for the first movie.



Just for kicks, try describing what makes Flash unique without bringing up occupation, what he likes, or what he looks like.