So uh, what was the Battle Frontier? I've heard people talk about it but I've never actually seen it.
It's pretty much a place where you can go and battle like at the battle tower but each have their own rule set.
One time it might be a surviavle area where you have to see how long you can go without healing between battles.
The next might be an adventure area, where you go though a pyrimaid and fight trainers and pokemon along the way.
The other you might use rentals and the next might be a dual pokemon challenge where instead of the usual three you only get to carry 2.
There were 8 of these areas, and each one had two badges you could collect. One badge is earned from winning 21 matches at the area in a row and the next is earned by winning 50. At the end of the 21 and 50 match you would fight a frontier brain./ AKA pretty much a gym leader
It was pretty much a second area where you could fight and do stuff.