In the fourth DLC at the end.
Atil Inac was born in 1975.
INAC Leonessa was created in 2001.
No
The Interplanetary Ninja Assassin Claptrap is the main enemy of the Claptrap's New Robot Revolution DLC. In it, the original Claptrap that you met when you got off the bus at the beginning, has been uploaded with combat programming by Hyperion, to take out some of the vault hunters. However it then rebelled, leading other claptraps in revolution. At the end of the DLC you will face the 'Mega' INAC first, a giant vehicle studded with gatling cannons and a giant laser. Then you'll fight INAC itself, though it can't really do much to hurt you. That ends the DLC.
Yes but you have to wait some time before you can fight him again.
If you mean can you fight your friends, yes you can, you need to enter an Arena, there are several to find, once in the Arena you can 'duel' with your friends.
Assuming you have the 4th Borderlands DLC, the Interplanetary Ninja Claptrap is the final boss.
Borderlands traditions tend to be mixed. Please specify WHICH borderlands you are referring to.
the creator of borderlands is Gearbox
Borderlands 2 is out now.
borderlands
Borderlands 2 was released on September 18th, 2012.