My version ( Advent Cirno)
 
Rainbow Dash : Cirno ( Both are blue and tomboyish)
 
Twilight Sparkle : Reisen Udongein Inaba ( Both are scientists and have assistances )
 
Pinkie Pie : Meiling Lockhart ( both are joyful and live in cafe/shops)
 
Fluttershy: Mystia Lorelei ( Both can fly and can sing)
 
Celestia: Yukari Yakumo
 
Luna : Eirin Yagokoro
 
Rarity : Leticia “Letty” Whiterock
 
Applejack : Shou Toramaru or Fujiwara no Mokou
 
Derpy : Utsuho Reiuji
 
Spoiled Rich : Sakuya Izayou
 
Moondancer : Patchouli Knowledge ( both have the same personality)
 
Diamond Tiara : Remilia Scarlet
 
Spike : Tewi Inaba

Ahhh, perfect, so Twilight can be Reimu in this case.
 
Honestly, Twilight has an assistant, Patchy has an assistant, sooooo Twi can still be Patchy, not that they are both purples / purplesmarts as well.  
How about Moondancer as Reimu? Would that work?

@DanmakuFony  
I think you meant to reply to the comment below mine.

@Ereiam  
Since when does Rainbow Dash wear pads? I know she commonly is drawn with having a flat chest, but I at least haven’t seen a picture with her wearing pads all the time. Besides, I see absolutely nothing else that Rainbow Dash and Sakuya Izayoi have in common.

@Roy-of-Asturia  
Yeaaaaaaaaaaah no. Dhalsim couldn’t have made that stretch, dude.

@Roy-of-Asturia  
I wasn’t even aware that Rainbow ever tried to compensate in this aspect.

@Tetrominon  
@Wiimeiser  
It’s P-A-D-S. Pads.
 
The pads joke.

@Roy-of-Asturia  
If that’s what I am thinking, then Hinanawi Tenshi would also be a match for Rainbow Dash (and personality-wise, a better one than Sakuya IMO).

Okay  

@Roy-of-Asturia  
Sulidae?

@thps48  
Hang on…
 

 
Patch from Animal Crossing. Now, I’m done. XD

@Background Pony #FDD7  
YOU WILL SUFFER FOR SAYING THAT!

@Background Pony #FDD7  

 
U wanna fite ill boosh ur hed in i sweer on me mum X3

Patchy is overrated

@the metal bronyhead  
Not always:
 

@Tetrominon  
That trait connection is more suggestive than you think.

@Roy-of-Asturia  
…I honestly have no idea what you mean by that, actually.
 
But I can tell you it’s gonna have to be one humdinger of a trait to outweigh a laundry list like “brash, egotistical speedster with little-to-no sense of subtlety and a penchant for being shipped with literally everyone and everything in sight”. :V

needs the Slippers

Come on Moondancer, you gotta be more forceful!  

@Tetrominon  
No misspelling.
 
Rainbow Dash = Izayoi Sakuya, because of…‘common’ trait connection, if ya know what we mean.

Since, Reimu is the mane character… <3<

@Roy-of-Asturia  
You misspelled “Rainbow Dash”.

@Ereiam  
Twilight Sparkle = Kirisame Marisa

@Ereiam  
She works as Patchy way better than Twi. To tell you the truth, other than than being purple and into books and magic, Twi had little in common with Patchouli character wise.

Make me.