If you don't mind, i can help! So if your OC is smarter, a game, or something like that, then you should make it a unicorn. if its a sporty, or a adventurous pony, then you should make it a Pegasus. and just in case its a stronger or flower pony, you should make it an earth pony (They have strengths too!) And If you can make up a good back story, its perfectly fine to make it an alicorn! I hope this helped!