Huh. That's strange. I considered the different cover legendaries, decided that I preferred Zekrom for his sleek appearance and cool typing, resisted the urge to make any unfunny jokes about the subject, and then chose White. I guess everyone makes decisions in different ways.
@Wolfen11: I guess you're right, but like R S E FR LG said, many of the children GameFreak is targeting with this game wouldn't understand the concept and would be confused. Then they would hurt themselves in their confusion :naughty:
Also, Legendary duos and trios tend to either have the same ability or abilities that compliment each other thematically. Groudon is causing harsh sunlight with Drought? Well, Kyogre is going to ruin that with rain from his Drizzle. Oh no, wait a sec, here comes Rayquaza, master of the sky, to shut them both down with Air Lock. Now try and apply that idea to Zek and Reshi given the ability you proposed. Woohoo! Zek can hit Ground Pokemon with Electric-typed attacks which they are normally immune too. Reshi can...hit Flash Fire Pokemon with Fire moves? That doesn't seem like equality to me.