Unit, I'm not sure what you've declared as your OC's abilities, but I can tell from his color scheme and his design that he's going to be disliked.
He's got red and black, which is universally accepted as one of the most badass color schemes in existence, and his mane is poofy and spiky. I've seen so many people make OCs of a similar variety that without knowing, I'd say yeah, he's a bit Mary Sue, but that's when you adjust various things to make him un-Sue.
I'm worrying about a similar problem with my OC, he's thin, white and blue, and doesn't have any characteristics that is far out from what you'd find in the show, but his ability is literally to unstoppably kill ponies because there's no way of fighting it. Oh, and he's also immortal, but that comes with enough downsides that I'm hoping he's just resting on "badass hero" status.