It's worth pointing out that the reasons she's hard is that Champion uses the closest thing the main game of any pokemon game has actually seen to a real, competitive team. A lot more thought has gone into it. You'd expect this stuff at Battle Tower, not at the League.

My first attempt at the Elite 4 my strategy became "Revive and chump with Dialga until her guy runs out of PP", which ultimately failed because I ran out of revives. Most of my guys were below level 50, and a lot of them still managed OHKOs (Cherrim basically destroyed the Ground-type member).

I then averaged my pokes out at level 55 and had a fairly smooth run. Staraptor especially is a monster if you get to at a decent level.

And I've found the GTS to be fairly interesting, even if it is loaded with hacked pokes.