How do you get the flow at more than 4 lines in Pokemon XD gale of darkness?

You can obtain a flow with more than 4 lines after completing the game one time and beginning a second playthrough. This allows you to have a flow of 5 lines from the beginning of the game. Later in the game, Mt. Battle will open up again and you can then win more matches to unlock flows with 6, 7, and 8 lines.