Dustox IS NOT a legend. That's just it. Just because a set is named Legend Maker doesn't mean that all of the cards in the set are legendary. Such was the case of Hidden Legends. By the same token, Pokémon-ex classification aren't restricted to the powerful monsters. Look at Mightyena. Look at Wigglytuff. Look at Sneasel. All of them are not the sharpest monsters around, but they were made into Pokémon-ex. By the same arguement, why would Neo: Genesis Azumarill have an attack with the same effect as the first Promo Articuno, only with more damage, even though Articuno has higher stats than Azumarill?
Because if the legendaries were made to be more powerful than the rest of the monsters, the game would grow stale, since everyone would be using legendaries. That's why they make it balanced in the TCG. In the GB games, legendaries with stat totals above 600 are banned in many tournaments because if they weren't, people would use and abuse them, like they did (and continue to do!) at the Pokémon Journeys Across America. I know that the GB games and the TCG are different, but the point that I am trying to illustrate is that if there is no balance in any game, it grows stale much more quickly.
Just look at it this way. If only the most powerful monsters were made into Pokémon-ex, there would be less variation, and less balance, thus less life in the game. They would have to reuse the same monsters more frequently, once they run out of powerful monsters, and everyone would be using Tyranitar, Zapdos, Mewtwo, Salamence, Armaldo, Arcanine, and others, as opposed to Wigglytuff, Pidgeot, Linoone, Dustox, Butterfree, Raticate, etc.
This is my stance on the issue. Others may feel differently.
