@Pashoo  
I know that all the “white” ponies in the show are actually very faintly tinted various colors. For example Vinyl Scratch is a shade of blue, and Princess Celestia is actually really faintly pink. That said, Vinyl is also eye-searingly high-luminosity whereas Celestia’s white color is a bit closer to a flat off-white or creamish color to make her appear much less “sharp” and make her coat clash less against her crazy trippy mane of wafty pastel doom.
 
And, like Pashoo said, even real blacks can be done. Getting too close to pure black is dangerous, but very dark black can be made to work so long as you tone back the saturation a bit and add contrast to it. Just be careful how you use it. Really dark, saturated black is a color reserved for the unusual and striking.

@Background Pony #1298  
Yeah, all of them are black, but they’re not all-black. @Background Pony #224F is right, you just need some sort of contrast, or to make the colors less extreme. Even Sombra, who’s a majority blackish still isn’t close to pure black, and is accented by his horn, cape, armor, and eyes. This oc’s cute, we just need to be able to see how cute.
 
Also funny enough, the same problem actually happens with one of the characters in the show, but on the opposite end of the spectrum. Shining Armor is pure white, and so in order to make his eyes visible, they had to make his eyes a different color, which is why his sclera is bluish/greenish. Rarity on the other hand, isn’t pure white, and so you can differentiate her eyes from her coat.

@Background Pony #1298  
These are all really good examples of how to do dark colors. Thunderlane is pretty pale and kinda dusty, and has that really pale mane to emphasize the sort of washed-out feeling with just enough blue to avoid being completely monotone. The exact same color scheme, more or less, but with slightly more saturated colors gives us a very nice striking look that still comes off feeling natural.
 
And then Nightmare Moon is color-inverted with all her sharp outlines and highlights picked out in blue to offset her incredibly heavy primary coloring along with the crazy spooky mane.
 
_{I still think Nightmare Moon’s hair makes her look bald though.}

@Background Pony #1298  
and after a long wild night with these three together, my oc is the final result…

@Background Pony #224F  
Still playing with color pallete… I will do it less dark next time

@Sparkler  
I´m still plaing with the color pallete. It´s an old pic TBH. Newer pics will be less edgy-look.

@hawthornbunny  
thanks

They all are black:  
 
 

Make either the main coat or the hair color much paler. Something that isn’t pure black would help, too. Even replacing the body shade with a midnight blue or something.

@Sparkler  
Brighten the outlines is a better solution.  
Although It’s a pretty lame oc, So the best idea is to scratch this garbage and start over

He needs to turn up the contrast dial…

Cool!