agreed most "legendary" pokemon are not very powerful. sure many of them have higher base stats than non-legendaries and some of them have better move pools but other than that there are only a few truly legendary pokemon that are overly powerful due to typing and stats. examples include the lati twins, mewtwo, arceus, and darkrai. these examples may not be correct because i know little to nothing about UU,OU,RU,& NU but the point is valid. so suck it up if you want to use pokemon you like then use them and throw in a decent legendary on your team just incase you do come up against other legendaries, it might not be abel to take on a whole team of them but it at least gives you a fighting chance.
Strive for an epic battle for all to see!