I beat the game and didn't get 120k points. I am writing this so you can know how to get the maximum amount of points.
When you first start up the game and select the normal mode press the window button to open up the menu. Go to Game Settings. Go to the "time" option and put it up as high as possible. It can go to 29M 59S. The go to the Difficutly option and set it down to level 1. Exit the settings. It will reset the game.
The score for this game is based entirely on how much time is on the clock when you win the round. By cranking up the time you will assure yourself that you will win with over 100 seconds left each time, thus getting the maximum amount of points. Points only accrue at the end of the round. I got this achievement after beating Act 6.
You can do this with anyone because you are able to save scum the game. At the beginning of every round press the window button and select "create reset point" which is the very top option. When you want to load the save state press the window button and select "exit to title screen." Select the normal game mode again and it will load you back into your save state. You can do this as much as you want so anytime you get ahead of the opponent in life save the game.
If you just want the easiest way you win use I Am Cully's guide from the Caravan achievement.
Character: Joe Kusanagi (the orange suit guy with black spiky hair)
Move: Joe's Special
When facing right: ← ↙ ↓↘ → + X
Simply use that over and over again to win. When you do the move go right back into holding backwards that way if the opponent blocks you will be blocking when they retaliate. The AI is not stupid. It will block the attack and get hits in. If you are smart and time your attack after they do an attack you will be able to get them consistently.
Also don't forget his CRAZY move. It can only be used when the opponent is on their red life bar and you fill up the CRAZY meter.
Joe's is: Up, Up/Back, Back, Forward + A (X button on the controller). The move has Joe send out a friend that runs across the screen. If the friend hits it instantly defeats the opponent, regardless of how much red health they have left.