The Battle Frontier is near Olivine city. You can have barely any badges and still go there. I think the developers were trying to make a good training ground for weaker trainers. Lame.
This Battle Frontier is an near exact copy of Platinum's and not Crystal's for one.
You can't go to the Battle Frontier until after you beat the Elite Four because it's not open yet.
Also, that's how all the Battle Frontier facilities work until you get a good winning streak going. Then it becomes impossibafjasklfhasj;h
It can get insanely impossible. Try to beat Thorton when he has a Latios, Moltres and a Marowak and you have Gallade, Electivire and Lucario. FREAKING LATIOS! Lucario-scorched, Gallade-dragon rushed, electivire-dragon rushed. There might be a lot of stage 1 pokemon like chimchar at first, but once you get past like 21 straight battles or so the game will have no quarrels about throwing salamence after tyranitar after garchomp after you.really? i think i beat it about 3 times. lost somewhere inbetween. how hard does it get?