This achievement is quite easy. In arcade mode, go to dragon editor and throw in a default dragon without spending any points in attributes. Now go to arcade (has to be single player). Pick your best dragon (Deadly Nadder) and ready up. Now pick the AI dragon as one of the default “no attribute” ones. You can easily win 10 times in a row without even losing your first health bar on hard. If you really are still having trouble with this (you won’t but just in case), you can make it 4vs1, an unfair fight in your advantage. To make things go really fast, just keep hitting rematch.