Stogi, you would have to have special maps for that and it would be interesting.
Modes I want to see again:
Classic Mode Return: I liked the classic 1 Player challenge mode. It was a set of basic challenges that changed because of the characters. It was a fun and quick way to game.
Race to the Finish: This was by far my favorite mini game, and it is sad that it was never expanded on. I would like to see Race to the Finish return in two forms. An online time race mode which has you trying to be your friends best time. These levels should be specially designed for each character so that the course can be extra devious and have a couple of short cuts.
But it should also come with a randomly generated map that can be played with 4 people at a time that are racing each other to the finish. This level could have unlockable and random skins representing different games.
Smash Volleyball or Smash Soccer: This is a simple game that has the characters attacking a ball like pong which the other team must hit back. Smash Attacks make the ball go much faster, and Special attacks can slow the ball down, speed it up, or help you set the ball up for another players attack. Sure it is basically Tekken Ball, but it sounds awesome.
Single Screen Challenges: This could be a Smash Puzzle mode, which has players trying to complete a puzzle task on a single screen with their characters. Each character can have 2 different puzzles