Pokemon Ruby and Pokemon Sapphire do not have the Battle Frontier, instead they only have the Battle Tower. It was not until Emerald version that the Battle Frontier was added to the game.
defeat the pokemon league
yes
it is not present in ruby. it is just there in emerald
You can't.
You will battle Groudon for your chance to capture it in Pokemon Omega Ruby after gaining more power.
no
It's in the battle frontier at the battle area
in the battle frontier next to the battle factory
You can get it at the Battle Tower
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 can battle him at the end of victory road