After doing a check in on his nemesis, Vlad Masters, Danny Phantom discovers that things have gotten weird. Vlad has sucked two creatures, Sonic the Hedgehog and Tails, into their universe, all for plans of world domination. In a race to return Sonic and Tails to their own worlds before Vlad can capture them, Danny and his friends team up with the creatures to get them home. Will Danny's world be safe, or will they all succumb to the obstacles Vlad has put before them?

Sonic and Mega Man are meeting again. But this time, it's far more deadly than either Sonic or Mega Man could have imagined. Everything robotic is turning evil, due to one mastermind. A single virus is spreading throughout both worlds, helping Dr. Wily in his plots to take over the world. As Sonic and Mega Man find each other again, will it be a happy meeting, or will every single robot, including one of the heroes, fight to the death?