I generally try and level my Dragons up as fast as I can, but I'm only just unlocking the silver shrines. Will a level 15 dragon race better than a ten? What about a 1 vs a 10?
Short Answer: No.
Long Answer: On the Dragon Track, it doesn't matter what level your dragon is, it is the types that matter. A race between a level 15 and a 10 would depend on the level. If the race theme was fire and the 15 level dragon was an ice type and the 10 was fire, the 10 would definitely win because it had better types. Same thing goes for 1 and 10, and any other combos. Whatever type matches better with the theme, that determines the winner. But if they are the same type of dragon, such as lightning and lightning, the one with the better boosting skills would win. When you get to the boosting line, tap it at the perfect time. Great, perfect, and even good lineups are helpful for racing. If you are only getting ok's or just completely ignoring them, don't. Even if all the other dragons are weak to the type. And always remember to check the theme, it gives you a good hint on what types it is.