Dunno about an official defintion but...You can never counter every threat in the DPPt metagame, there are just too many of them to effectively have a solution, with just six pokemon. By trying to make the metagame balanced..you eliminate the broken aspects so that each player actually has a shot at beating the other. 'Hax' throws a wrench in this though, so things like 'hax' clause try and alleviate this a little.
Of course you gotta know how to construct a well made team to TRY and counter the current metagames top threats, but by removing certain aspects of the game (ex. the tiers), and providing movesets, standard or not, it gives every player a shot at winning in a battle.
Balanced might not even be the right term, maybe Orderly is more correct.
---------- Post added at 02:22 PM ---------- Previous post was at 02:19 PM ----------
Legendaries? You mean things like heatran, azelf, celebi jirachi, etc? The ones I just mentioned are all OU.
The only reason someone should complain by being beaten 'legendaries' is if they got beat by an UBER tier legendary pokemon (ex Mewtwo), while they were using a team consisting of pokemon from a lower tier...because well, it's not fair to use Uber tier pokemon against OU/UU/NU's
Even then, why would anyone complain? People should know the rules laid out for a battle there about to get into..
---------- Post added at 02:26 PM ---------- Previous post was at 02:22 PM ----------
I'd say they do. If your talking about OU legendary pokemon (azelf, celebi etc..)
There base stats, coupled with there movesets and typings obviously put them above some other pokemon, thats why most legendary pokemon are in high usage.
I assume your talking about JUST OU legendaries because..to say Uber tier pokemon don't inherently carry an advantage over other pokemon is..foolish