This wasn't a very well done quiz, due to the fact that there were too many various solutions that could be argued into being correct.
The question was a bit vague, the hint wasn't too clear or helpful. As well, given the fact of the Pokemon choice, a lot of solutions could have came up being "correct".
I got the right answer despite all of this, because I noticed each Pokemon had a gem of some sort, but only Dragonair didn't have one on it's forehead.
Of course, one can argue, All the Pokemon do have gems, but Weavile has a coin/amulet on it's head. So the choice would have been Weavile...
Quite sneaky though I have to admit.