@AC97  
Considering what all of Equestria was up against, I think it would make sense for everypony and everycreature to unite as one.
 
Also, I like thinking these so that this fandom can be accurate with their “Everyone is Here!” memes.

@Red-Supernova
 
To be fair, arguably they’d be too powerful to really represent the spirit of what they were going for, because a powerful alicorn and a unicorn as powerful as Shining would overshadow the contributions of the rest, because you would easily go “oh, that shield was mostly him/those two,” and/or “they did most of the work in inconveniencing them,” aside from the logistics of why they’re there, when there’s no one to rally them, and them knowing they might be too late if they showed up.
 
It’s not like Lightning Dust where her being there would amount to probably a similar result assuming you’re going with her being in-character doing that which comes down to opinion.

@AC97  
I like to think Cadance and the rest of her family joined in with the rest of Equestria for the final battle.

@Background Pony Number 17
 
I mean, really, if she’s already contributing to putting Sombra on the backfoot and such (with Chrysalis), she has a lot going for her to begin with.
 
She’d quite possibly be one of the most potent alicorns when she gets older, if she cared about magic in any way along the lines of how her aunt, mother, or father do. Possibly more dangerous than if Starlight were an alicorn, if not just rivalling her.
 
…So not the worst backup plan, if it involves pulling a bit of a Samurai Jack with her.

@AC97
 

Ah, yes, the “don’t spend these powerful ponies immediately” plan.
 
…I really wish we got to see Cadance be outright awesome again in S9. She’s quite possibly the best fighter out of the alicorns, even compared to Twilight, aside from her raw power being nothing to scoff at.
 
(best she did was almost attack Sombra in spite of the hostage plan, and ruin his mind control hold with the Crystal Heart with Spike’s help of “weaken Crystals,” forcing him to retreat, and be ready to throw down if he didn’t)

“It says here every other fanart of us is going to have me be a full head taller than you, for some reason.”
 
“Dang it, I knew that shot with me next to the crystal guard would bite me in the rear.”