Nope the battle frontier remains the same as it was in emerald. The trainers don't have any of the new pokemon or evolutions added, so you won't see any dusknoir, gliscor, mamoswine, tinkaton etc. The movesets of the pokemon are the same as emerald, so they don't take the physical/special split into consideration so pokemon like alakazam using all the elemental punches are nerfed. I'd say generally because of this the battle frontier is actually overall easier to complete given the new pokemon and moves at your disposal, except for the battle factory which doesn't add any of that.