Is it just me or any of the comment bellow watch the episode. After Twilight save them they literally used their magic to fight Cozy but with the bell in her hoof. Then they don’t have a chance.

@PastelBacon  
Map episodes often had one or more of the participants look or act foolish for a good chunk of the episode; Twilight isn’t alone in that case. The Parent Map, Triple Threat, Surf and/or Turf all had one or more characters being portrayed as foolish for large chunks of the episode. Twilight was just as essential to the resolution as Fluttershy in that episode.
 
Personally, while a number of the later Twilight episodes were kind of weak (especially A Trivial Pursuit), there were still some gems (The Point of No Return, School Daze, Fame and Misfortune, etc). I think her overall competence over those seasons were the highest all series, especially when she was acting in a mentor or advisor role for a different character focused episode (A Horse Shoe-In, The Washouts, Dragon Dropped, Molt Down, Surf and/or Turf, etc). Fame and Misfortune, etc). Her combat prowess also got a large bump in season 9, being able to match Sombra in a beam clash at the end of The Beginning of the End and personally outperforming both Starswirl and Starlight in The Ending of the End.
 
I do however agree that it would have been very nice to see them have some combat success in the finale (other than the offscreen fight while they were depowered). I don’t think I would have changed this moment (as it shows Twilight’s barrier capability off very nicely), but I think I would have had Celestia and Luna defeat Cozy Glow, only for her to be saved like normal with the arrival of the other two. They could have their magic sapped by the bell at that point.

@Background Pony #E473
 
Twilight’s usefulness starting spazzing around after Season 5.  
Half the time she felt useless, especially in that one S5 Episode where she tried her damn hardest, only for 5 minutes till the end, Fluttershy stepped into be like “Oh but hey” and everything is magically fixed.
 
No other map episode did that. Each character had their own issue, but with that one, Twilight was made to look a fool.
 
Also, I have no real headcanon anymore, the only one was a disprovable one with Grogar, I just want to feel like Luna and Celestia can do more than be fodder for villains, or in S4’s case, Discord’s shenanigans.
 
Even the show writers themself know how useless they made them considering they joked about it in the episode the final season when they had Dash say “Of all the times we could have had their help, they choose now?”
 
Twilight became a mixed bag after Season 5.  
She had her best episode ever in Amending Fences, and it was all downhill from there most of the time, with the occasional gem.

@PastelBacon  
I’m not wrong, though.  

 
Define useful. If useful is ‘reaching into your mind and do the thing your favorite fanfic does/conform to my headcanon,’ then you’re a black hole of a person who will never be happy even if they got what they wanted. And “for once”? Someone has a selective memory.  
(I also guess Twilight doesn’t count as a Princess or useful.)

@Background Pony #E473  
Ah yes, I was waiting for your kind.  
The kind who calls any form of criticism whining.
 
It’s a legit annoyance that needs to change in at least one thing.  
Have an actual useful Princess for once.

You are just a bunch of whiners. Yeesh.

@Background Pony #4060  
The trope of literally anything from the beginning of filmmaking and video games:
 
Princesses are useless.  
For once, I wish this trope would NOT be part of something.

@Valsion
 
You also can’t forget how she suggested and helped carry out “redecorating,” or the very first thing you hear in the next part.

And with that act Cozy pretty much destroys any argument for her defense. Assaulting the princesses should result in a harsh punishment.

@Background Pony #958D  
P.C: Hell, Cadance was the only one of us who actually tried to do something.

@Background Pony #19E2  
P.C: Because we been in this situation before during the movie, remember Tempest and her magic petrified ball. The magic shield can’t even handle a small magic ball and you want us to hold a magic blast form an alicorn.  
P.L: Oh…you’re right.

@Background Pony #19E2  
Because jabbing at the Princesses is so kewl and not overdone

@Background Pony #19E2  
“Its called the worf effect sister…”

“Tia, why are we so useless?”