You first need 21 wins in a row, then you challenge the head (in other words, you have to win 3 sets of 7 battles without losing once). Then, you will face him...
After you defeat the Elite Four, You will unlock the battle frontier. The battle factory is at the West side of the battle frontier.
you have to beat the battle frontier brain
It is very simple. Challenge each battle frontier building and win three times in a row and on the 7th battle on your third challenge someone will tell you that the frontier brain of that facility will want to challenge you. ( You have no choice but to battle them)
either way works
The Battle Factory is located at the Battle Frontier.In order to get to the Battle Frontier you must beat the Elite Four.When you go to the Battle Frontier check your trainer card.Check the Battle Frontier's map and on the bootom-left corner you will see the name Battle Factory.
It's in the battle frontier at the battle area
in the battle frontier next to the battle factory
You can't
The Battle Factory
4 or more
yes
No, but the Frontier Brain of Sinoh is there as an Elite Four member.