This can be done solo, one person one controller. This can be combo'd with Party People. For the combo, simply sill all ten slots while you're in the team selection menu.
Now for Walk Over. Go to play, party battle, single controller, and choose your characters and your "opponent's" characters. Now just have your main avatar's team win every single round, plus fast money, and the achievement will pop when you get to the Rematch/Main Menu screen during the credits.