Who of our characters got the worst treatment in EQG?
Spike? Luna? Twilight?

2449788 Rainbow Dash. For some reason she is a soccer player. It would make much more sense for her to be a runner. And she has a very weird hairdo. (Seriously, what's up with that?) She is also OOC in both universes. I'm only going to say this once. Just once. SHE WORE A FUCKING SKIRT! SHE HATES GIRLY STUFF! THAT'S WHY SHE'S A FUCKING TOMBOY! Would she if this was a better movie? HELL NO! God, I hate this fucking movie so bad.

2452847 What about she keep repeating "That's so awesome", how many times does she say that?

2454686 IDK I'm not watching it again to find out.

6. Spike. Yeah he's low on the list since yeah there's the dog thing, which is crap and opened an unnecessary plot hole (Why didn't twilight just show him to celestia to prove she's from an alternate world? If spike was a kid like the CMC (why the fuck are they in high school anyway?) we wouldn't have this plothole since a talking kid is not strange at all.) but apart from that he was actually rather good all things considered. Strangely, being a dog aside Spike got it better in EQG than he did in a lot of the episodes as of late (i'm looking at you Spike At Your Service.)
5. Flash Sentry. Yeah, it's just sad when your shitty forced love interest makes it on the list of "characters who got it badly." Though he actually did. He got it so bad that even a lot of the hasdrones say he's completely unnecessary: He got zero development, next to no lines (certainly none of any importance) and came off as little more than a glorified self insert OC that one of the execs forced the writers to insert because his kid wanted his bad fanfiction to be canon. Actually that kinda describes this whole movie now that I think about it.
4. The Main 5. I'm just going to lump them all into one area since they pretty much all suffer from the same problem. Instead of the characters we love, they became cardboard cutouts of the characters we love based on (I'm going to sound like a broken record here) what bad fanfiction writers cast them as. IE Pinkie Pie is a 4th wall breaking annoyance that makes the Double Rainboom pinkie pie seem in character. Rainbow is a Soccer Player (seriously? Why Soccer?! Rainbow's thing is SPEED. Not (just) competitive sports. She should be a Runner or something? Or was that just too boring?) that spouts awesome every other sentence. Applejack... didn't get it all that bad admittedly. Fluttershy so shy that she's stupid, so much so that even the FIM Fluttershy would have to roll her eyes. And Rarity... is bland and boring.
Not to mention they're cast off as complete idiots. Like everyone else.
3. Luna. As if being downgraded from the secondary ruler of an entire nation to a vice principal of a high school wasn't bad enough, she's cast as a complete and utter incompetent dunce who not once questions the validity of the pictures she's given in an age of photoshop and the like, especially when she's given them by a student who's known to be a troublemaker. Even worse considering that she should have been able to spot GLUED ON PICTURES.
Basically, it makes her seem completely out of touch with her students and so utterly incompetent it's a wonder she still has a job. And while you can excuse the FIM Luna for that, seeing as she's been stuck in the moon for 1000 years, for the EQG one there's NO excuse for it.
2. Twilight Sparkle. She's gone from the intelligent dork that would solve problems logically into the "hay I gotta become teh fall formal pricesezz!!" we see in every high school drama. Not only is she turned into a mary stu, but also a completely useless mary stu that doesn't actually do anything of value at all.
1. Friendship is Magic as a whole. Okay seriously, you know something is wrong when they have to resort to this whole High School cliche. Especially when we have a pretty well established fantasy world with magic and mythical creatures and such.

2455004 You know, the sad thing for Flash Sentry is that the people who want him back want only for FlashLight to happen and dosen't give a crap for him.
But i guess that's okay, cause love wasn't the main part of the story duhrhurh.

2449861 Why did they did that to him?
: At least I still have swag....