So, what exactly is Rumble Mode all about? In truth, it's about whatever the player wants it to be. It can be a way to try out new powers or characters. It can be a way to challenge yourself by taking on single player levels using completely different characters. Heck, it's a great place to train yourself in just about every aspect of the game.
The Rumble Room feature can be accessed from the Main Menu. Once you've entered, you're then able to choose from the five different modes of play. These include, "Battle in the Rumble Room", "Campaign Mission", "Action Mode", "Iron Man" and "Race".

"Battle in the Rumble Room" allows you to select (or have randomly selected) two teams (yours and the AI) and fight it out on the map of your choice. This mode is great if you're just looking for some fast action without any frills.