Sorry, I disagree. Your OC is beautiful as Equestrian unicorn. She has a nice pastel color scheme, very symbolic bootiemark and does not have weird additions like glowing tentacles, halfmeter fangs and stuff. Рonies with leg markings are not unusual in Equestria and Rosie's colors are pretty common.
The main reason, why Equestrian ponies are looking so similar is technology of animation. Simplier = cheaper. But we can see that Equestrians can look really unique and interesting. Look at Sassy Saddles, Sunburst or Flutterpony's brother (forgot his name). And my favorite is Bulk Biceps! (Looks like equestrian pone a way less than your OC, LOL)
Sorry, pone, but Big Mac still has pastel color scheme. He isn't bright red. Even if he's one of brightest ponies I've ever seen.