Yeah, Trixpyrus just seems so obvious after it was pointed out to me.
 
But for Frisk I’d go with Spike. It’d have to be an AU Spike to allow for the whole fight vs mercy thing, but then that goes for any Frisk replacement; there are no canon characters that are THAT malleable.
 
I was thinking it’d start with some sort of feral Spike in the Everfree Forest being found by Fluttershy… which would make Discord fit alarmingly well as Flowey for the first scene, as he might go too far, only for Shy to tell him off. Don’t really like him in that role otherwise though, he seems much more fitting as Sans to me.

@Turnways_Flip  
Oh crap, you’re totally right… The great Papyrus, and the Great and Powerful Trixie, it’s perfect!

How is it that everyone’s been feverishly clamoring that their candidate should have been x or y character and nobody has pointed out that the only match for Papyrus is Trixie

@GhostTheCapitalist  
Not implying that ponies aren’t. It just means its hard to compare, because the odds of all those details matching decrease rapidly the more details are involved.

@Keith Mowz
 

I would switch Celly and Luna. Celestia is a good mother figure and Luna is a good pony but things she did are somewhat messed up.
 
But otherwise - amazing! I love it :3

Honestly, very few characters match up with the Undertale cast particularly well, because all of them are such well developed, fleshed out and distinct characters.

@DoomPony  
That could definitely work. Though now I kind of want to see Twilight’s actual parents as Toriel and Asgore.

@FanOfMostEverything  
I agree with AJ as Frisk, but I think Discord would make a better Sans, mostly because I can’t see him as Flowey. I think Twilight would make an acceptable Asriel given the other characters.

PonyTale…

Umm, I’ve gotta give you items to raise your affection statistic, first!
 
That’ll increase the chance of a successful outcome to the date!
 
Right…?
 
Anyway, d-don’t worry! I’m prepared!
 
I-I’ve been stockpiling gifts in anticipation for a date like this!
 
F-first, I’ve got…
 
Some rainbow mane conditioner!
 
…
 
Um, maybe you can’t use that.
 
But!!!
 
I also brought a preening brush for your wings!
 
Your, uh…Wings…
 
Uh, well, how about…
 
This magical spear repair kit, that I…
 
Um…
 
Hey, let’s forget about the items!
 
Let’s just start the date!
 
DATING!! START!!

Honestly, I’d switch AJ and Twilight. Sans is brilliant and a terrifyingly powerful mage, but is consumed by ennui because of the logical consequences of living in a world where his every accomplishment can be wiped clean by another’s will. Meanwhile, Frisk’s DETERMINATION and Applejack’s stubbornness are both positive traits as much as they are negative ones.

Frisklight Sparkle  
Toriluna  
Flowcord  
Applesans  
Pinkie Pyrus  
Undash  
Alphshy  
Rariton  
Aslestia
 
Best I could come up with, XD

@PonyPon  
Look at her sleeping on the job.  
 
Totally lazy. 100%  
No but seriously, RD should have been Sans, Luna Undyne and Celestia as Toriel.

Aj a lazy bones?
 
Perish the thought.

@Align  
Naaah, I don’t see Flutters throwing fire magic around to teach someone a lesson. And look at Toriel’s dialogue, and tell me which voice sounds like the best match. Also she’s a good match for Alphys, the shut-in with poor social skills and crippling anxieties.
 
Plus if this is anything to go by , Fluttershy is a total anime dork too.

I love this so much and while i don’t agree with all of the choices, I can’t but laugh at the idea of Pinkie wearing Papy’s “Cool Dude” outfit…..Can Derpy be Temmie?

Celestia should be Toriel, good/comic Sombra should be Asgore, Luna should be Sans +/- Derpy as Papyrus… I just can’t see AJ as someone with Sans powers and badassery.  
Pinkie as Papyrus may work but AJ as Sans no. RD and Fluttershy are ok
 
heck even Cadance could be Toriel and Shining be Asgore

@armadiloeater  
Fluttershy?

Pretty great, but I can’t see anyone but Celestia as Toriel.