Ridiculous quiz. There's no definition of what 'powerful' means or how they're ranked. It also doesn't say it's limited to Gen IV and earlier. If it's based on Base Stat Totals, how can you ignore Manaphy and Darkrai when they have 600 like most of the others? And how can you rank them if they all have 600? Still got 100% by guess work, but this quiz is stupid and should be taken down.
http://www.serebii.net/pokedex-dp/stat/all.shtml