After the reset of the universe, Mario is invited for free cake by Peach. He enters the castle to get the cake, gathering his closest pals and friends along the way, only to find out that there is none...
Sonic arrives at the Castle to hang out with Mario and his pals before Eggman comes by and tries to ruin the party and traps his friends and the animals inside! It's now up to Mario and Sonic to defeat Eggman!