Based after the Cartoon Network series of the same name, Grim Adventures (for consoles) plays very much like an arena fighter based on Power Stone.
Regarding the plot - one day, Grim's Mojo Balls are unleashed into Endsville, giving all the residents supernatural rage. This leads into mass fighting and mayhem, and it is up to Grim, Billy, Mandy, and Irwin to figure out who unleashed the balls.
Each character has special abilities and moves, as well as weapons to utilize. Each character also has a Mojo meter, which is a power bar. If filled once, it can be used to deal heavy damage, and if filled twice, it can be used to knock out all players.
The game spans across several levels that are destructible and feature roughly most of the major characters from Grim Adventures, and have various single-player and multiplayer modes.